The auto-routing path in src/sse/handlers/chat.ts called `getSettings()`
on every `auto` / `auto/\*` request, but the symbol was never imported in
this module (only `getCachedSettings` was). The runtime ReferenceError
crashed the request with a 500 before any routing could happen.
Replace the call with `getCachedSettings` (already imported, identical
return shape, plus the cached variant benefits the auto-routing hot path).
A regression-guard test scans chat.ts to fail loudly if a future refactor
re-introduces the unimported call pattern.
