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/drizzle/meta/_journal.json

@@ -71,6 +71,13 @@
       "when": 1776855591000,
       "tag": "0009_analytics_consent",
       "breakpoints": true
+    },
+    {
+      "idx": 10,
+      "version": "6",
+      "when": 1778300000000,
+      "tag": "0010_remove_branding",
+      "breakpoints": true
     }
   ]
 }