Point beta FE at beta.backend.hesychia.ai (#64) (#65)

## Summary
- Closes #64
- Beta FE was still calling `beta.chatbackend.aimloperations.com`, which no longer resolves, so login failed with Axios `ERR_NETWORK`
- Point REST/WS env URLs at the live backend: `beta.backend.hesychia.ai`

## Test plan
- [ ] Redeploy beta FE with updated `.env.beta`
- [ ] Confirm built bundle `baseURL` is `https://beta.backend.hesychia.ai/api/`
- [ ] Sign in on https://beta.hesychia.ai succeeds (no `ERR_NETWORK`)
- [ ] Chat WebSocket connects via `wss://beta.backend.hesychia.ai/ws/chat_again/`Reviewed-on: #65

llm-fe/.env.beta

@@ -1,8 +1,7 @@
-# Beta API hosts (current). Target public product domain: hesychia.ai
-# Flip these to hesychia.ai API hosts when server-infra / DNS cut over.
+# Beta API hosts — public product domain hesychia.ai
 REACT_APP_DEPLOY_ENV=beta
-REACT_APP_BACKEND_REST_API_BASE_URL=https://beta.chatbackend.aimloperations.com/api/
-REACT_APP_BACKEND_WS_API_BASE_URL=wss://beta.chatbackend.aimloperations.com/ws/chat_again/
+REACT_APP_BACKEND_REST_API_BASE_URL=https://beta.backend.hesychia.ai/api/
+REACT_APP_BACKEND_WS_API_BASE_URL=wss://beta.backend.hesychia.ai/ws/chat_again/
 # Tianji website id for Hesychia beta (distinct from prod so analytics stay separate).
 # Create "Hesychia Beta" in Tianji UI (workspace cm7w8087y020lddswyhamadj2), then paste id here.
 REACT_APP_TIANJI_WEBSITE_ID=cms38bw671mf9n5jjw3xp1j3q