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.

tests/integration/test-server.ts

@@ -36,7 +36,6 @@ import { analyticsRoutes } from "../../apps/api/src/routes/analytics.js";
 import { apiKeyRoutes } from "../../apps/api/src/routes/api-keys.js";
 import { auditLogRoutes } from "../../apps/api/src/routes/audit-log.js";
 import { registerBatchRoutes } from "../../apps/api/src/routes/batch.js";
-import { brandingRoutes } from "../../apps/api/src/routes/branding.js";
 import { docsRoutes } from "../../apps/api/src/routes/docs.js";
 import { fileRoutes } from "../../apps/api/src/routes/files.js";
 import { registerPipelineRoutes } from "../../apps/api/src/routes/pipeline.js";
@@ -109,9 +108,6 @@ export async function buildTestApp(): Promise<TestApp> {
   // Settings routes
   await settingsRoutes(app);
 
-  // Branding routes
-  await brandingRoutes(app);
-
   // Teams routes
   await teamsRoutes(app);