feat(docker): deploy PORT06 portfolio runner via docker compose

Wire the Docker image and compose service for the capital-pool portfolio
paper trader (src.portfolio.runner) instead of the single-leg multi_runner:

- Dockerfile: copy full scripts/ (runner imports scripts.analysis.* and
  scripts.portfolios._defs via sleeves.py) and portfolios.yml.
- docker-compose.yml: service "portfolio" / container pythagoras-portfolio,
  command override to src.portfolio.runner, mount portfolios.yml, healthcheck
  on data/portfolios/ status.json.
- .gitignore: ignore portfolio runtime state (data/portfolio_paper, data/portfolios).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -1,17 +1,18 @@
 services:
-  paper-trader:
+  portfolio:
     build: .
-    container_name: pythagoras-multi
+    container_name: pythagoras-portfolio
     restart: unless-stopped
+    command: ["uv", "run", "python", "-m", "src.portfolio.runner"]
     volumes:
       - ./data:/app/data
-      - ./strategies.yml:/app/strategies.yml:ro
+      - ./portfolios.yml:/app/portfolios.yml:ro
     env_file:
       - .env
     environment:
       - PYTHONUNBUFFERED=1
     healthcheck:
-      test: ["CMD", "python", "-c", "import os; assert any(f.endswith('status.json') for r,d,fs in os.walk('/app/data/paper_trades') for f in fs)"]
+      test: ["CMD", "python", "-c", "import os; assert any(f.endswith('status.json') for r,d,fs in os.walk('/app/data/portfolios') for f in fs)"]
       interval: 120s
       timeout: 10s
       retries: 3