chore: dockerize api proxy and add gitignore

Add a Docker-based FastAPI proxy skeleton (charter §4) for parity across
dev / homelab VPS / fly.io, plus root .gitignore for Godot 4.7 and Python.

- api/Dockerfile: python:3.12-slim, non-root, PORT-aware CMD
- api/app/main.py: /health + five role endpoint stubs (§4)
- api/requirements.txt: fastapi/uvicorn/httpx/pydantic, pinned
- docker-compose.yml: local dev with live reload
- api/fly.toml: prod deploy stub with /health check
- api/.env.example: key lives in the proxy, never the client (§4)
- .gitignore: ignores .env, whitelists .env.example

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

docker-compose.yml

@@ -0,0 +1,17 @@
+# Local dev — run the proxy in Docker with live reload.
+#   docker compose up --build
+# Ollama runs on the homelab (charter §4), not here — point OLLAMA_BASE_URL at it.
+services:
+  api:
+    build: ./api
+    ports:
+      - "8000:8000"
+    env_file:
+      - ./api/.env
+    environment:
+      PORT: 8000
+    # Mount source + reload so edits are live without a rebuild.
+    volumes:
+      - ./api/app:/app/app:ro
+    command: >
+      uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload