Scaffold FastAPI backend skeleton with health probes

Phase 0 foundation. uv-managed FastAPI app (package=false, runs from source via uv run). Layered seams in place: app/api for routers, app/core for config (pydantic-settings, fully env-driven) and the async SQLAlchemy engine; service/repository/domain layers land with the data model.

Exposes /health (liveness) and /health/ready (Postgres reachability via SELECT 1, 503 on failure) so the deploy wiring is verifiable before any data model exists. Includes a liveness test and the resolved uv.lock. Ignore pytest/ruff/mypy caches.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

.gitignore

@@ -25,6 +25,11 @@ target/
 dist/
 build/
 
+# Tooling caches
+.pytest_cache/
+.ruff_cache/
+.mypy_cache/
+
 # Logs
 *.log
 npm-debug.log*