Fix 113 hardening issues across entire Go backend

Security:
- Replace all binding: tags with validate: + c.Validate() in admin handlers
- Add rate limiting to auth endpoints (login, register, password reset)
- Add security headers (HSTS, XSS protection, nosniff, frame options)
- Wire Google Pub/Sub token verification into webhook handler
- Replace ParseUnverified with proper OIDC/JWKS key verification
- Verify inner Apple JWS signatures in webhook handler
- Add io.LimitReader (1MB) to all webhook body reads
- Add ownership verification to file deletion
- Move hardcoded admin credentials to env vars
- Add uniqueIndex to User.Email
- Hide ConfirmationCode from JSON serialization
- Mask confirmation codes in admin responses
- Use http.DetectContentType for upload validation
- Fix path traversal in storage service
- Replace os.Getenv with Viper in stripe service
- Sanitize Redis URLs before logging
- Separate DEBUG_FIXED_CODES from DEBUG flag
- Reject weak SECRET_KEY in production
- Add host check on /_next/* proxy routes
- Use explicit localhost CORS origins in debug mode
- Replace err.Error() with generic messages in all admin error responses

Critical fixes:
- Rewrite FCM to HTTP v1 API with OAuth 2.0 service account auth
- Fix user_customuser -> auth_user table names in raw SQL
- Fix dashboard verified query to use UserProfile model
- Add escapeLikeWildcards() to prevent SQL wildcard injection

Bug fixes:
- Add bounds checks for days/expiring_soon query params (1-3650)
- Add receipt_data/transaction_id empty-check to RestoreSubscription
- Change Active bool -> *bool in device handler
- Check all unchecked GORM/FindByIDWithProfile errors
- Add validation for notification hour fields (0-23)
- Add max=10000 validation on task description updates

Transactions & data integrity:
- Wrap registration flow in transaction
- Wrap QuickComplete in transaction
- Move image creation inside completion transaction
- Wrap SetSpecialties in transaction
- Wrap GetOrCreateToken in transaction
- Wrap completion+image deletion in transaction

Performance:
- Batch completion summaries (2 queries vs 2N)
- Reuse single http.Client in IAP validation
- Cache dashboard counts (30s TTL)
- Batch COUNT queries in admin user list
- Add Limit(500) to document queries
- Add reminder_stage+due_date filters to reminder queries
- Parse AllowedTypes once at init
- In-memory user cache in auth middleware (30s TTL)
- Timezone change detection cache
- Optimize P95 with per-endpoint sorted buffers
- Replace crypto/md5 with hash/fnv for ETags

Code quality:
- Add sync.Once to all monitoring Stop()/Close() methods
- Replace 8 fmt.Printf with zerolog in auth service
- Log previously discarded errors
- Standardize delete response shapes
- Route hardcoded English through i18n
- Remove FileURL from DocumentResponse (keep MediaURL only)
- Thread user timezone through kanban board responses
- Initialize empty slices to prevent null JSON
- Extract shared field map for task Update/UpdateTx
- Delete unused SoftDeleteModel, min(), formatCron, legacy handlers

Worker & jobs:
- Wire Asynq email infrastructure into worker
- Register HandleReminderLogCleanup with daily 3AM cron
- Use per-user timezone in HandleSmartReminder
- Replace direct DB queries with repository calls
- Delete legacy reminder handlers (~200 lines)
- Delete unused task type constants

Dependencies:
- Replace archived jung-kurt/gofpdf with go-pdf/fpdf
- Replace unmaintained gomail.v2 with wneessen/go-mail
- Add TODO for Echo jwt v3 transitive dep removal

Test infrastructure:
- Fix MakeRequest/SeedLookupData error handling
- Replace os.Exit(0) with t.Skip() in scope/consistency tests
- Add 11 new FCM v1 tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/dto/requests/task.go

@@ -71,7 +71,7 @@ type CreateTaskRequest struct {
 // UpdateTaskRequest represents the request to update a task
 type UpdateTaskRequest struct {
 	Title              *string          `json:"title" validate:"omitempty,min=1,max=200"`
-	Description        *string          `json:"description"`
+	Description        *string          `json:"description" validate:"omitempty,max=10000"`
 	CategoryID         *uint            `json:"category_id"`
 	PriorityID         *uint            `json:"priority_id"`
 	FrequencyID        *uint            `json:"frequency_id"`

internal/dto/responses/document.go

@@ -21,8 +21,9 @@ type DocumentUserResponse struct {
 type DocumentImageResponse struct {
 	ID       uint   `json:"id"`
 	ImageURL string `json:"image_url"`
-	MediaURL string `json:"media_url"` // Authenticated endpoint: /api/media/document-image/{id}
+	MediaURL string `json:"media_url"`           // Authenticated endpoint: /api/media/document-image/{id}
 	Caption  string `json:"caption"`
+	Error    string `json:"error,omitempty"`      // Non-empty when the image could not be resolved
 }
 
 // DocumentResponse represents a document in the API response
@@ -35,7 +36,6 @@ type DocumentResponse struct {
 	Title         string                `json:"title"`
 	Description   string                `json:"description"`
 	DocumentType  models.DocumentType   `json:"document_type"`
-	FileURL       string                `json:"file_url"`
 	MediaURL      string                `json:"media_url"` // Authenticated endpoint: /api/media/document/{id}
 	FileName      string                `json:"file_name"`
 	FileSize      *int64                `json:"file_size"`
@@ -80,7 +80,6 @@ func NewDocumentResponse(d *models.Document) DocumentResponse {
 		Title:         d.Title,
 		Description:   d.Description,
 		DocumentType:  d.DocumentType,
-		FileURL:       d.FileURL,
 		MediaURL:      fmt.Sprintf("/api/media/document/%d", d.ID), // Authenticated endpoint
 		FileName:      d.FileName,
 		FileSize:      d.FileSize,
@@ -104,12 +103,16 @@ func NewDocumentResponse(d *models.Document) DocumentResponse {
 
 	// Convert images with authenticated media URLs
 	for _, img := range d.Images {
-		resp.Images = append(resp.Images, DocumentImageResponse{
+		imgResp := DocumentImageResponse{
 			ID:       img.ID,
 			ImageURL: img.ImageURL,
 			MediaURL: fmt.Sprintf("/api/media/document-image/%d", img.ID), // Authenticated endpoint
 			Caption:  img.Caption,
-		})
+		}
+		if img.ImageURL == "" {
+			imgResp.Error = "image source URL is missing"
+		}
+		resp.Images = append(resp.Images, imgResp)
 	}
 
 	return resp

internal/dto/responses/task.go

@@ -281,13 +281,15 @@ func NewTaskListResponse(tasks []models.Task) []TaskResponse {
 	return results
 }
 
-// NewKanbanBoardResponse creates a KanbanBoardResponse from a KanbanBoard model
-func NewKanbanBoardResponse(board *models.KanbanBoard, residenceID uint) KanbanBoardResponse {
+// NewKanbanBoardResponse creates a KanbanBoardResponse from a KanbanBoard model.
+// The `now` parameter should be the start of day in the user's timezone so that
+// individual task kanban columns are categorized consistently with the board query.
+func NewKanbanBoardResponse(board *models.KanbanBoard, residenceID uint, now time.Time) KanbanBoardResponse {
 	columns := make([]KanbanColumnResponse, len(board.Columns))
 	for i, col := range board.Columns {
 		tasks := make([]TaskResponse, len(col.Tasks))
 		for j, t := range col.Tasks {
-			tasks[j] = NewTaskResponse(&t)
+			tasks[j] = NewTaskResponseWithTime(&t, board.DaysThreshold, now)
 		}
 		columns[i] = KanbanColumnResponse{
 			Name:        col.Name,
@@ -306,13 +308,15 @@ func NewKanbanBoardResponse(board *models.KanbanBoard, residenceID uint) KanbanB
 	}
 }
 
-// NewKanbanBoardResponseForAll creates a KanbanBoardResponse for all residences (no specific residence ID)
-func NewKanbanBoardResponseForAll(board *models.KanbanBoard) KanbanBoardResponse {
+// NewKanbanBoardResponseForAll creates a KanbanBoardResponse for all residences (no specific residence ID).
+// The `now` parameter should be the start of day in the user's timezone so that
+// individual task kanban columns are categorized consistently with the board query.
+func NewKanbanBoardResponseForAll(board *models.KanbanBoard, now time.Time) KanbanBoardResponse {
 	columns := make([]KanbanColumnResponse, len(board.Columns))
 	for i, col := range board.Columns {
 		tasks := make([]TaskResponse, len(col.Tasks))
 		for j, t := range col.Tasks {
-			tasks[j] = NewTaskResponse(&t)
+			tasks[j] = NewTaskResponseWithTime(&t, board.DaysThreshold, now)
 		}
 		columns[i] = KanbanColumnResponse{
 			Name:        col.Name,