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/database/database.go

@@ -5,6 +5,8 @@ import (
 	"time"
 
 	"github.com/rs/zerolog/log"
+	"github.com/spf13/viper"
+	"golang.org/x/crypto/bcrypt"
 	"gorm.io/driver/postgres"
 	"gorm.io/gorm"
 	"gorm.io/gorm/logger"
@@ -376,13 +378,23 @@ func migrateGoAdmin() error {
 	}
 	db.Exec(`CREATE INDEX IF NOT EXISTS idx_goadmin_site_key ON goadmin_site(key)`)
 
-	// Seed default admin user only on first run (ON CONFLICT DO NOTHING).
+	// Seed default GoAdmin user only on first run (ON CONFLICT DO NOTHING).
 	// Password is NOT reset on subsequent migrations to preserve operator changes.
-	db.Exec(`
-		INSERT INTO goadmin_users (username, password, name, avatar)
-		VALUES ('admin', '$2a$10$t.GCU24EqIWLSl7F51Hdz.IkkgFK.Qa9/BzEc5Bi2C/I2bXf1nJgm', 'Administrator', '')
-		ON CONFLICT DO NOTHING
-	`)
+	goAdminUsername := viper.GetString("GOADMIN_ADMIN_USERNAME")
+	goAdminPassword := viper.GetString("GOADMIN_ADMIN_PASSWORD")
+	if goAdminUsername == "" || goAdminPassword == "" {
+		log.Warn().Msg("GOADMIN_ADMIN_USERNAME and/or GOADMIN_ADMIN_PASSWORD not set; skipping GoAdmin admin user seed")
+	} else {
+		goAdminHash, err := bcrypt.GenerateFromPassword([]byte(goAdminPassword), bcrypt.DefaultCost)
+		if err != nil {
+			return fmt.Errorf("failed to hash GoAdmin admin password: %w", err)
+		}
+		db.Exec(`
+			INSERT INTO goadmin_users (username, password, name, avatar)
+			VALUES (?, ?, 'Administrator', '')
+			ON CONFLICT DO NOTHING
+		`, goAdminUsername, string(goAdminHash))
+	}
 
 	// Seed default roles
 	db.Exec(`INSERT INTO goadmin_roles (name, slug) VALUES ('Administrator', 'administrator') ON CONFLICT DO NOTHING`)
@@ -393,15 +405,17 @@ func migrateGoAdmin() error {
 	db.Exec(`INSERT INTO goadmin_permissions (name, slug, http_method, http_path) VALUES ('Dashboard', 'dashboard', 'GET', '/') ON CONFLICT DO NOTHING`)
 
 	// Assign admin user to administrator role (if not already assigned)
-	db.Exec(`
-		INSERT INTO goadmin_role_users (role_id, user_id)
-		SELECT r.id, u.id FROM goadmin_roles r, goadmin_users u
-		WHERE r.slug = 'administrator' AND u.username = 'admin'
-		AND NOT EXISTS (
-			SELECT 1 FROM goadmin_role_users ru
-			WHERE ru.role_id = r.id AND ru.user_id = u.id
-		)
-	`)
+	if goAdminUsername != "" {
+		db.Exec(`
+			INSERT INTO goadmin_role_users (role_id, user_id)
+			SELECT r.id, u.id FROM goadmin_roles r, goadmin_users u
+			WHERE r.slug = 'administrator' AND u.username = ?
+			AND NOT EXISTS (
+				SELECT 1 FROM goadmin_role_users ru
+				WHERE ru.role_id = r.id AND ru.user_id = u.id
+			)
+		`, goAdminUsername)
+	}
 
 	// Assign all permissions to administrator role (if not already assigned)
 	db.Exec(`
@@ -448,15 +462,25 @@ func migrateGoAdmin() error {
 
 	// Seed default Next.js admin user only on first run.
 	// Password is NOT reset on subsequent migrations to preserve operator changes.
-	var adminCount int64
-	db.Raw(`SELECT COUNT(*) FROM admin_users WHERE email = 'admin@honeydue.com'`).Scan(&adminCount)
-	if adminCount == 0 {
-		log.Info().Msg("Seeding default admin user for Next.js admin panel...")
-		db.Exec(`
-			INSERT INTO admin_users (email, password, first_name, last_name, role, is_active, created_at, updated_at)
-			VALUES ('admin@honeydue.com', '$2a$10$t5hGjdXQLxr9Z0193qx.Tef6hd1vYI3JvrfX/piKx2qS9UvQ41I9O', 'Admin', 'User', 'super_admin', true, NOW(), NOW())
-		`)
-		log.Info().Msg("Default admin user created: admin@honeydue.com")
+	adminEmail := viper.GetString("ADMIN_EMAIL")
+	adminPassword := viper.GetString("ADMIN_PASSWORD")
+	if adminEmail == "" || adminPassword == "" {
+		log.Warn().Msg("ADMIN_EMAIL and/or ADMIN_PASSWORD not set; skipping Next.js admin user seed")
+	} else {
+		var adminCount int64
+		db.Raw(`SELECT COUNT(*) FROM admin_users WHERE email = ?`, adminEmail).Scan(&adminCount)
+		if adminCount == 0 {
+			log.Info().Str("email", adminEmail).Msg("Seeding default admin user for Next.js admin panel...")
+			adminHash, err := bcrypt.GenerateFromPassword([]byte(adminPassword), bcrypt.DefaultCost)
+			if err != nil {
+				return fmt.Errorf("failed to hash admin password: %w", err)
+			}
+			db.Exec(`
+				INSERT INTO admin_users (email, password, first_name, last_name, role, is_active, created_at, updated_at)
+				VALUES (?, ?, 'Admin', 'User', 'super_admin', true, NOW(), NOW())
+			`, adminEmail, string(adminHash))
+			log.Info().Str("email", adminEmail).Msg("Default admin user created")
+		}
 	}
 
 	return nil