feat(agent-office): scaffold backend — config, db, models, Dockerfile

SQLite DB layer with WAL mode, agent_config/tasks/logs/telegram_state tables,
2 seeded agents, full CRUD, and passing test suite (7/7).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent-office/Dockerfile

@@ -0,0 +1,10 @@
+FROM python:3.12-alpine
+ENV PYTHONUNBUFFERED=1
+
+WORKDIR /app
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY . .
+
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]