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>

frontend/src/components/CharacterCard.tsx

@@ -0,0 +1,17 @@
+import { Link } from "react-router-dom";
+
+import { Character } from "../api/characters";
+
+export default function CharacterCard({ character }: { character: Character }) {
+  return (
+    <Link
+      to={`/characters/${character.id}`}
+      className="block rounded-lg border border-slate-800 bg-slate-900 p-4 hover:border-amber-500"
+    >
+      <h2 className="text-lg font-semibold text-slate-100">{character.name}</h2>
+      <p className="text-sm text-slate-400">
+        {character.race ?? "?"} · {character.char_class ?? "?"} · Stufe {character.level}
+      </p>
+    </Link>
+  );
+}