Add a `/week` command: an LLM-summarized review of the notes captured over the last 7 daily Drive files. **Why:** `/today` covers the day; `/week` surfaces themes, recurring topics, and open loops across the week — the higher-altitude second-brain view. (Reworked from the original calendar-briefing idea because the calendar infrastructure lives on an unmerged branch; `/week` is buildable on `main` today and reuses the existing OpenRouter LLM.) **Scope:** - New `weekly.py`; register `/week` in `bot.py`. - List the daily markdown files in the Drive folder, take the most recent 7 by date. - Parse the captured message blocks, feed them to the LLM (reuse `scheduler.create_llm`) for a themed summary: recurring topics, action items, notable notes. - Graceful when there is little/no data or the LLM call fails. Auth-gated.