docs: add logging anti-patterns to AGENTS.md

- Log to console only (must use backend/app/log/)

- Commit log files to git (must be .gitignored)

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

AGENTS.md

@@ -69,6 +69,8 @@ app/
 - Missing document metadata — breaks source attribution
 - Add authentication — public demo only
 - Mobile-first design — desktop only at this stage
+- Log to console only — all backend logs must go to `backend/app/log/` directory
+- Commit log files to git — log files must be `.gitignore`d
 
 ## UNIQUE STYLES
 - **Dual ASR trigger**: automatic (on transcript update) + manual "Ask from Video" button