Add landing page, redesign emails, and return updated task on completion

- Integrate landing page into Go app (served at root /)
- Add STATIC_DIR config for static file serving
- Redesign all email templates with modern dark theme styling
- Add app icon to email headers
- Return updated task with kanban_column in completion response
- Update task DTO to include kanban column for client-side state updates

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/TASK_KANBAN_LOGIC.md

@@ -6,16 +6,16 @@ This document describes how tasks are categorized into kanban columns for displa
 
 Tasks are organized into 6 kanban columns based on their state and due date. The categorization logic is implemented in `internal/repositories/task_repo.go` in the `GetKanbanData` and `GetKanbanDataForMultipleResidences` functions.
 
-## Columns
+## Columns Summary
 
-| Column | Name | Color | Description |
-|--------|------|-------|-------------|
-| 1 | **Overdue** | `#FF3B30` (Red) | Tasks past their due date |
-| 2 | **Due Soon** | `#FF9500` (Orange) | Tasks due within the threshold (default 30 days) |
-| 3 | **Upcoming** | `#007AFF` (Blue) | Tasks due beyond the threshold or with no due date |
-| 4 | **In Progress** | `#5856D6` (Purple) | Tasks with status "In Progress" |
-| 5 | **Completed** | `#34C759` (Green) | Tasks with at least one completion record |
-| 6 | **Cancelled** | `#8E8E93` (Gray) | Tasks marked as cancelled |
+| Column | Name | Color | Button Types | Description |
+|--------|------|-------|--------------|-------------|
+| 1 | **Overdue** | `#FF3B30` (Red) | edit, complete, cancel, mark_in_progress | Tasks past their due date |
+| 2 | **Due Soon** | `#FF9500` (Orange) | edit, complete, cancel, mark_in_progress | Tasks due within the threshold (default 30 days) |
+| 3 | **Upcoming** | `#007AFF` (Blue) | edit, complete, cancel, mark_in_progress | Tasks due beyond the threshold or with no due date |
+| 4 | **In Progress** | `#5856D6` (Purple) | edit, complete, cancel | Tasks with status "In Progress" |
+| 5 | **Completed** | `#34C759` (Green) | view | Tasks with at least one completion record |
+| 6 | **Cancelled** | `#8E8E93` (Gray) | uncancel, delete | Tasks marked as cancelled |
 
 ## Categorization Flow
 
@@ -86,7 +86,8 @@ if task.IsCancelled {
 }
 ```
 - **Condition**: `is_cancelled = true`
-- **Actions Available**: `uncancel`, `delete`
+- **Button Types**: `uncancel`, `delete`
+- **Rationale**: Cancelled tasks can be restored (uncancel) or permanently removed (delete)
 
 ### 2. Completed
 ```go
@@ -97,7 +98,8 @@ if len(task.Completions) > 0 {
 ```
 - **Condition**: Task has at least one `TaskCompletion` record
 - **Note**: A task is considered completed based on having completion records, NOT based on status
-- **Actions Available**: `view`
+- **Button Types**: `view`
+- **Rationale**: Completed tasks are read-only for historical purposes; users can view completion details and photos
 
 ### 3. In Progress
 ```go
@@ -107,7 +109,8 @@ if task.Status != nil && task.Status.Name == "In Progress" {
 }
 ```
 - **Condition**: Task's status name is exactly `"In Progress"`
-- **Actions Available**: `edit`, `complete`
+- **Button Types**: `edit`, `complete`, `cancel`
+- **Rationale**: In-progress tasks can be edited, marked complete, or cancelled if work is abandoned
 
 ### 4. Due Date Based Categories (only for tasks not cancelled, completed, or in progress)
 
@@ -118,7 +121,8 @@ if task.DueDate.Before(now) {
 }
 ```
 - **Condition**: `due_date < current_time`
-- **Actions Available**: `edit`, `cancel`, `mark_in_progress`
+- **Button Types**: `edit`, `complete`, `cancel`, `mark_in_progress`
+- **Rationale**: Overdue tasks need urgent attention - can complete immediately, start working on them, edit the due date, or cancel if no longer needed
 
 #### Due Soon
 ```go
@@ -128,14 +132,28 @@ if task.DueDate.Before(threshold) {
 ```
 - **Condition**: `current_time <= due_date < (current_time + days_threshold)`
 - **Default threshold**: 30 days
-- **Actions Available**: `edit`, `complete`, `mark_in_progress`
+- **Button Types**: `edit`, `complete`, `cancel`, `mark_in_progress`
+- **Rationale**: Due soon tasks are approaching their deadline - users can complete early, start working, reschedule, or cancel
 
 #### Upcoming
 ```go
 upcoming = append(upcoming, task)
 ```
 - **Condition**: `due_date >= (current_time + days_threshold)` OR `due_date IS NULL`
-- **Actions Available**: `edit`, `cancel`
+- **Button Types**: `edit`, `complete`, `cancel`, `mark_in_progress`
+- **Rationale**: Future tasks may need to be completed early (ahead of schedule), started, rescheduled, or cancelled
+
+## Button Types Reference
+
+| Button Type | Action | Description |
+|-------------|--------|-------------|
+| `edit` | Update task | Modify task details (title, description, due date, category, etc.) |
+| `complete` | Create completion | Mark task as done with optional notes and photos |
+| `cancel` | Cancel task | Mark task as cancelled (soft delete, can be uncancelled) |
+| `mark_in_progress` | Start work | Change status to "In Progress" to indicate work has begun |
+| `view` | View details | View task and completion details (read-only) |
+| `uncancel` | Restore task | Restore a cancelled task to its previous state |
+| `delete` | Hard delete | Permanently remove task (only for cancelled tasks) |
 
 ## Column Metadata
 
@@ -145,7 +163,7 @@ Each column includes metadata for the mobile clients:
 {
     Name:        "overdue_tasks",          // Internal identifier
     DisplayName: "Overdue",                // User-facing label
-    ButtonTypes: []string{"edit", "cancel", "mark_in_progress"},  // Available actions
+    ButtonTypes: []string{"edit", "complete", "cancel", "mark_in_progress"},
     Icons:       map[string]string{        // Platform-specific icons
         "ios": "exclamationmark.triangle",
         "android": "Warning"
@@ -156,6 +174,17 @@ Each column includes metadata for the mobile clients:
 }
 ```
 
+### Icons by Column
+
+| Column | iOS Icon | Android Icon |
+|--------|----------|--------------|
+| Overdue | `exclamationmark.triangle` | `Warning` |
+| Due Soon | `clock` | `Schedule` |
+| Upcoming | `calendar` | `Event` |
+| In Progress | `hammer` | `Build` |
+| Completed | `checkmark.circle` | `CheckCircle` |
+| Cancelled | `xmark.circle` | `Cancel` |
+
 ## Days Threshold Parameter
 
 The `daysThreshold` parameter (default: 30) determines the boundary between "Due Soon" and "Upcoming":
@@ -185,7 +214,7 @@ The following tasks are excluded from the kanban board entirely:
     {
       "name": "overdue_tasks",
       "display_name": "Overdue",
-      "button_types": ["edit", "cancel", "mark_in_progress"],
+      "button_types": ["edit", "complete", "cancel", "mark_in_progress"],
       "icons": {
         "ios": "exclamationmark.triangle",
         "android": "Warning"
@@ -194,13 +223,86 @@ The following tasks are excluded from the kanban board entirely:
       "tasks": [...],
       "count": 2
     },
-    // ... other columns
+    {
+      "name": "due_soon_tasks",
+      "display_name": "Due Soon",
+      "button_types": ["edit", "complete", "cancel", "mark_in_progress"],
+      "icons": {
+        "ios": "clock",
+        "android": "Schedule"
+      },
+      "color": "#FF9500",
+      "tasks": [...],
+      "count": 5
+    },
+    {
+      "name": "upcoming_tasks",
+      "display_name": "Upcoming",
+      "button_types": ["edit", "complete", "cancel", "mark_in_progress"],
+      "icons": {
+        "ios": "calendar",
+        "android": "Event"
+      },
+      "color": "#007AFF",
+      "tasks": [...],
+      "count": 10
+    },
+    {
+      "name": "in_progress_tasks",
+      "display_name": "In Progress",
+      "button_types": ["edit", "complete", "cancel"],
+      "icons": {
+        "ios": "hammer",
+        "android": "Build"
+      },
+      "color": "#5856D6",
+      "tasks": [...],
+      "count": 3
+    },
+    {
+      "name": "completed_tasks",
+      "display_name": "Completed",
+      "button_types": ["view"],
+      "icons": {
+        "ios": "checkmark.circle",
+        "android": "CheckCircle"
+      },
+      "color": "#34C759",
+      "tasks": [...],
+      "count": 15
+    },
+    {
+      "name": "cancelled_tasks",
+      "display_name": "Cancelled",
+      "button_types": ["uncancel", "delete"],
+      "icons": {
+        "ios": "xmark.circle",
+        "android": "Cancel"
+      },
+      "color": "#8E8E93",
+      "tasks": [...],
+      "count": 1
+    }
   ],
   "days_threshold": 30,
   "residence_id": "123"
 }
 ```
 
+## Design Decisions
+
+### Why "In Progress" doesn't have "mark_in_progress"
+Tasks already in the "In Progress" column are already marked as in progress, so this action doesn't make sense.
+
+### Why "Completed" only has "view"
+Completed tasks represent historical records. Users can view them but shouldn't be able to uncomplete or modify them. If a task was completed incorrectly, the user should delete the completion record through the completion detail view.
+
+### Why "Cancelled" has "delete" but others don't
+Hard deletion is only available for cancelled tasks as a final cleanup action. For active tasks, users should cancel first (soft delete), then delete if truly needed. This prevents accidental data loss.
+
+### Why all active columns have "cancel"
+Users should always be able to abandon a task they no longer need, regardless of its due date or progress state.
+
 ## Code Location
 
 - **Repository**: `internal/repositories/task_repo.go`