fix(dolt): remove bd sync from AGENTS.md

SQLite-era instruction causing agents to run deprecated bd sync.
With Dolt backend, there is no sync - database is live.

Part of hq-e4eefc (Dolt migration epic)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

AGENTS.md

@@ -45,7 +45,6 @@ bd update <id> --acceptance "acceptance criteria"
 4. **PUSH TO REMOTE** - This is MANDATORY:
    ```bash
    git pull --rebase
-   bd sync
    git push
    git status  # MUST show "up to date with origin"
    ```