#6524: fix(ui): use local favicon instead of CDN URL with expired signature

## Problem The sidebar logo in the Control UI fails to load with a 403 Forbidden error. The CDN URL `mintcdn.com/clawhub/...` has an expired or domain-locked signature that fails for self-hosted and Docker deployments. ## Solution Replace the external CDN URL with the local `/favicon.svg` (absolute path) which is already bundled in the UI public assets. ## Changes - `ui/src/ui/app-render.ts`: Replace CDN URL with `/favicon.svg` ## Testing - Tested on local Docker deployment - Logo now loads correctly from local assets - Used absolute path per Greptile feedback (relative `./` would break on nested routes) Fixes #6135 Fixes #6365