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>

.env.example

@@ -0,0 +1,25 @@
+# Copy this file to .env and fill in real values. Never commit .env.
+
+# x.ai API (Grok) — DM model. Get a key at https://console.x.ai
+XAI_API_KEY=
+
+# Auth secrets — generate with: python -c "import secrets; print(secrets.token_urlsafe(32))"
+JWT_SECRET=
+RESET_PASSWORD_SECRET=
+VERIFICATION_TOKEN_SECRET=
+
+# Postgres
+POSTGRES_USER=dnd
+POSTGRES_PASSWORD=
+POSTGRES_DB=dnd
+DATABASE_URL=postgresql+asyncpg://dnd:changeme@postgres:5432/dnd
+
+# SMTP (password reset emails). Leave empty in dev — emails are logged to console instead.
+SMTP_HOST=
+SMTP_PORT=587
+SMTP_USER=
+SMTP_PASSWORD=
+SMTP_FROM=no-reply@dungeonsdragons.tstratmann.de
+
+# Frontend / CORS
+FRONTEND_ORIGIN=http://localhost:5173