Add Phase 1 MVP: D&D text-adventure server

FastAPI + Postgres backend with fastapi-users auth, games/characters
CRUD, and a WebSocket chat endpoint where an x.ai Grok DM narrates
play, rolls dice, and maintains character sheets via tool calls.
React + Tailwind frontend covers registration/login, game list and
creation, participation-code join flow, character viewer, and a
real-time chat session view. Docker Compose skeleton (Postgres +
backend) included; Caddy/frontend container wiring is deferred to
the deploy milestone.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,17 @@
+.env
+__pycache__/
+*.pyc
+.venv/
+venv/
+node_modules/
+dist/
+build/
+*.egg-info/
+.pytest_cache/
+.mypy_cache/
+caddy_data/
+caddy_config/
+pgdata/
+frontend/dist/
+*.tsbuildinfo
+.DS_Store