feat: remove app name and logo customization feature

Users can no longer customize the app name or logo. The branding API
endpoints, permission, frontend UI, env vars (APP_NAME, MAX_LOGO_SIZE_KB),
and all related tests are removed. Includes a migration to clean up
branding data from existing databases.

apps/api/src/index.ts

@@ -21,7 +21,6 @@ import { analyticsRoutes } from "./routes/analytics.js";
 import { apiKeyRoutes } from "./routes/api-keys.js";
 import { auditLogRoutes } from "./routes/audit-log.js";
 import { registerBatchRoutes } from "./routes/batch.js";
-import { brandingRoutes } from "./routes/branding.js";
 import { docsRoutes } from "./routes/docs.js";
 import { registerFeatureRoutes } from "./routes/features.js";
 import { fileRoutes } from "./routes/files.js";
@@ -180,9 +179,6 @@ await analyticsRoutes(app);
 // Feature management routes (AI feature bundle install/uninstall)
 await registerFeatureRoutes(app);
 
-// Branding routes (logo upload/serve/delete)
-await brandingRoutes(app);
-
 // Teams routes
 await teamsRoutes(app);