Add webhook logging, pagination, middleware, migrations, and prod hardening

- Webhook event logging repo and subscription webhook idempotency
- Pagination helper (echohelpers) with cursor/offset support
- Request ID and structured logging middleware
- Push client improvements (FCM HTTP v1, better error handling)
- Task model version column, business constraint migrations, targeted indexes
- Expanded categorization chain tests
- Email service and config hardening
- CI workflow updates, .gitignore additions, .env.example updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/handlers/residence_handler_test.go

@@ -25,7 +25,7 @@ func setupResidenceHandler(t *testing.T) (*ResidenceHandler, *echo.Echo, *gorm.D
 	userRepo := repositories.NewUserRepository(db)
 	cfg := &config.Config{}
 	residenceService := services.NewResidenceService(residenceRepo, userRepo, cfg)
-	handler := NewResidenceHandler(residenceService, nil, nil)
+	handler := NewResidenceHandler(residenceService, nil, nil, true)
 	e := testutil.SetupTestRouter()
 	return handler, e, db
 }