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/models/task.go

@@ -181,88 +181,6 @@ func (t *Task) IsDueSoon(days int) bool {
 	return !effectiveDate.Before(now) && effectiveDate.Before(threshold)
 }
 
-// GetKanbanColumn returns the kanban column name for this task using the
-// Chain of Responsibility pattern from the categorization package.
-// Uses UTC time for categorization.
-//
-// For timezone-aware categorization, use GetKanbanColumnWithTimezone.
-func (t *Task) GetKanbanColumn(daysThreshold int) string {
-	// Import would cause circular dependency, so we inline the logic
-	// This delegates to the categorization package via internal/task re-export
-	return t.GetKanbanColumnWithTimezone(daysThreshold, time.Now().UTC())
-}
-
-// GetKanbanColumnWithTimezone returns the kanban column name using a specific
-// time (in the user's timezone). The time is used to determine "today" for
-// overdue/due-soon calculations.
-//
-// Example: For a user in Tokyo, pass time.Now().In(tokyoLocation) to get
-// accurate categorization relative to their local date.
-func (t *Task) GetKanbanColumnWithTimezone(daysThreshold int, now time.Time) string {
-	// Note: We can't import categorization directly due to circular dependency.
-	// Instead, this method implements the categorization logic inline.
-	// The logic MUST match categorization.Chain exactly.
-
-	if daysThreshold <= 0 {
-		daysThreshold = 30
-	}
-
-	// Start of day normalization
-	startOfDay := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
-	threshold := startOfDay.AddDate(0, 0, daysThreshold)
-
-	// Priority 1: Cancelled
-	if t.IsCancelled {
-		return "cancelled_tasks"
-	}
-
-	// Priority 2: Archived (goes to cancelled column - both are "inactive" states)
-	if t.IsArchived {
-		return "cancelled_tasks"
-	}
-
-	// Priority 3: Completed (NextDueDate nil with completions)
-	hasCompletions := len(t.Completions) > 0 || t.CompletionCount > 0
-	if t.NextDueDate == nil && hasCompletions {
-		return "completed_tasks"
-	}
-
-	// Priority 4: In Progress
-	if t.InProgress {
-		return "in_progress_tasks"
-	}
-
-	// Get effective date: NextDueDate ?? DueDate
-	var effectiveDate *time.Time
-	if t.NextDueDate != nil {
-		effectiveDate = t.NextDueDate
-	} else {
-		effectiveDate = t.DueDate
-	}
-
-	if effectiveDate != nil {
-		// Normalize effective date to same timezone for calendar date comparison
-		// Task dates are stored as UTC but represent calendar dates (YYYY-MM-DD)
-		normalizedEffective := time.Date(
-			effectiveDate.Year(), effectiveDate.Month(), effectiveDate.Day(),
-			0, 0, 0, 0, now.Location(),
-		)
-
-		// Priority 5: Overdue (effective date before today)
-		if normalizedEffective.Before(startOfDay) {
-			return "overdue_tasks"
-		}
-
-		// Priority 6: Due Soon (effective date before threshold)
-		if normalizedEffective.Before(threshold) {
-			return "due_soon_tasks"
-		}
-	}
-
-	// Priority 7: Upcoming (default)
-	return "upcoming_tasks"
-}
-
 // TaskCompletion represents the task_taskcompletion table
 type TaskCompletion struct {
 	BaseModel