feat: add chat group daily summarizer

- Telegram collector (Telethon MTProto) with checkpoint-based message fetching
- Claude API summarization via proxy (haiku model)
- Dashboard page with date picker, markdown summary, raw message drill-down
- Separate container lifecycle from dashboard for stable Telethon sessions
- Shared SQLite DB mounted read-only into dashboard

chat-summarizer/Dockerfile

@@ -0,0 +1,6 @@
+FROM python:3.12-slim
+WORKDIR /app
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+COPY . .
+CMD ["python", "-u", "main.py"]