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>

backend/app/models/character.py

@@ -0,0 +1,29 @@
+import uuid
+from datetime import datetime
+
+from sqlalchemy import ForeignKey, Integer, String, Text, func
+from sqlalchemy.dialects.postgresql import JSONB, UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class Character(Base):
+    __tablename__ = "characters"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    owner_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("users.id"), nullable=False, index=True
+    )
+    name: Mapped[str] = mapped_column(String(length=200), nullable=False)
+    race: Mapped[str | None] = mapped_column(String(length=100), nullable=True)
+    char_class: Mapped[str | None] = mapped_column(String(length=100), nullable=True)
+    level: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
+    stats: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
+    description: Mapped[str] = mapped_column(Text, nullable=False, default="")
+    created_at: Mapped[datetime] = mapped_column(server_default=func.now(), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        server_default=func.now(), onupdate=func.now(), nullable=False
+    )