Migrate from Gin to Echo framework and add comprehensive integration tests

Major changes:
- Migrate all handlers from Gin to Echo framework
- Add new apperrors, echohelpers, and validator packages
- Update middleware for Echo compatibility
- Add ArchivedHandler to task categorization chain (archived tasks go to cancelled_tasks column)
- Add 6 new integration tests:
  - RecurringTaskLifecycle: NextDueDate advancement for weekly/monthly tasks
  - MultiUserSharing: Complex sharing with user removal
  - TaskStateTransitions: All state transitions and kanban column changes
  - DateBoundaryEdgeCases: Threshold boundary testing
  - CascadeOperations: Residence deletion cascade effects
  - MultiUserOperations: Shared residence collaboration
- Add single-purpose repository functions for kanban columns (GetOverdueTasks, GetDueSoonTasks, etc.)
- Fix RemoveUser route param mismatch (userId -> user_id)
- Fix determineExpectedColumn helper to correctly prioritize in_progress over overdue

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/task/predicates/predicates_test.go

@@ -187,6 +187,8 @@ func TestIsOverdue(t *testing.T) {
 	now := time.Now().UTC()
 	yesterday := now.AddDate(0, 0, -1)
 	tomorrow := now.AddDate(0, 0, 1)
+	// Start of today - this is what a DATE column stores (midnight)
+	startOfToday := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
 
 	tests := []struct {
 		name     string
@@ -216,6 +218,17 @@ func TestIsOverdue(t *testing.T) {
 			now:      now,
 			expected: false,
 		},
+		{
+			name: "not overdue: task due today (start of day)",
+			task: &models.Task{
+				NextDueDate: timePtr(startOfToday),
+				IsCancelled: false,
+				IsArchived:  false,
+				Completions: []models.TaskCompletion{},
+			},
+			now:      now, // Current time during the day
+			expected: false,
+		},
 		{
 			name: "not overdue: cancelled task",
 			task: &models.Task{
@@ -291,6 +304,8 @@ func TestIsDueSoon(t *testing.T) {
 	yesterday := now.AddDate(0, 0, -1)
 	in5Days := now.AddDate(0, 0, 5)
 	in60Days := now.AddDate(0, 0, 60)
+	// Start of today - this is what a DATE column stores (midnight)
+	startOfToday := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
 
 	tests := []struct {
 		name          string
@@ -311,6 +326,18 @@ func TestIsDueSoon(t *testing.T) {
 			daysThreshold: 30,
 			expected:      true,
 		},
+		{
+			name: "due soon: task due today (start of day)",
+			task: &models.Task{
+				NextDueDate: timePtr(startOfToday),
+				IsCancelled: false,
+				IsArchived:  false,
+				Completions: []models.TaskCompletion{},
+			},
+			now:           now, // Current time during the day
+			daysThreshold: 30,
+			expected:      true,
+		},
 		{
 			name: "not due soon: beyond threshold",
 			task: &models.Task{