Scaffold FastAPI + MySQL + Keycloak service with devcontainer

Sets up the project skeleton:

- FastAPI app factory with lifespan, request-id middleware, and RFC 9457
  problem+json error handlers
- Async SQLAlchemy 2.0 over MySQL (asyncmy), with a constraint naming
  convention in place before the first migration and async Alembic
- Keycloak as a pure resource server: OIDC discovery, cached JWKS with
  rotation-aware refresh, and require_roles dependencies
- Devcontainer running MySQL 8.4 and Keycloak 26.7 as compose siblings,
  with the realm (clients, roles, test users) imported on first boot
- Test suite covering the endpoints plus the token validator itself,
  exercised against a locally generated RSA keypair
- uv packaging, ruff, mypy --strict, pre-commit, Gitea CI, prod Dockerfile

Two Keycloak-in-containers traps are handled explicitly and documented in
the README: the issuer/internal-URL split (the browser sees localhost:8080,
the API sees keycloak:8080) and the audience mapper that stops Keycloak
issuing tokens with aud=account.

The devices resource is a placeholder proving the routing -> auth -> ORM ->
migration path end to end; replace it with the real domain.

Co-Authored-By: Claude Opus 5 <[email protected]>

.devcontainer/Dockerfile

@@ -0,0 +1,16 @@
+FROM mcr.microsoft.com/devcontainers/python:1-3.13-bookworm
+
+# `mysql` CLI for poking at the database during development.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends default-mysql-client \
+    && rm -rf /var/lib/apt/lists/*
+
+# Pinned rather than :latest so a rebuild months from now is reproducible.
+COPY --from=ghcr.io/astral-sh/uv:0.9.7 /uv /uvx /usr/local/bin/
+
+ENV UV_PROJECT_ENVIRONMENT=/workspaces/v2x-server/.venv \
+    # Bind mounts can't be hardlinked into, which is uv's default install mode.
+    UV_LINK_MODE=copy \
+    UV_COMPILE_BYTECODE=1 \
+    PYTHONUNBUFFERED=1 \
+    PATH=/workspaces/v2x-server/.venv/bin:$PATH