feat(server): mint API + Postgres schema + manual adapter (PR 1)

Source-agnostic license issuance service. FastAPI app fronts a
Postgres `licenses` table; the only currently-wired source is
`manual` (operator mints via /internal/mint). Gumroad webhook
adapter lands in PR 2.

Key design points:

- Signing reuses src/license/crypto.py via a COPY into the image
  (single source of truth — blobs minted server-side verify against
  the same embedded pubkey on the buyer's machine).
- Source adapter Protocol (app/adapters/base.py) is the seam for
  Gumroad / Lemon Squeezy / Stripe in later PRs; Mint API speaks
  only SaleEvent / RefundEvent.
- (source, source_order_id) UNIQUE composite gives idempotent
  webhook retries without double-mint.
- JSONB type uses with_variant(JSON, 'sqlite') so the same models
  drive both Postgres prod and SQLite tests (no testcontainers dep).
- Bearer-token auth on /internal/*; the IP-loopback guard was
  removed after the docker bridge made it fight legitimate prod
  traffic (nginx defense + Bearer remain).
- Secrets resolved via *_FILE env vars pointing at
  /run/secrets/<name>, so passwords never appear in `docker inspect`.

21 unit tests (SQLite in-memory, StaticPool) plus a real-Postgres
docker-compose smoke test in server/scripts/smoke.sh that builds the
image, runs the alembic migration, mints a license, verifies the
signature against the host dev pubkey, and checks the DB row.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/app/routes/public.py

@@ -0,0 +1,27 @@
+"""Public (internet-facing) routes.
+
+For PR 1: only ``/health``. The webhook receiver and renewal portal
+land in PR 2 and PR 3 respectively.
+"""
+
+from __future__ import annotations
+
+from fastapi import APIRouter, Depends
+from sqlalchemy import text
+from sqlalchemy.exc import SQLAlchemyError
+from sqlalchemy.orm import Session
+
+from app.db import get_session
+
+router = APIRouter()
+
+
+@router.get("/health")
+def health(session: Session = Depends(get_session)) -> dict:
+    """Liveness + DB reachability. Cheap; safe to hit on a tight cadence."""
+    db_ok = True
+    try:
+        session.execute(text("SELECT 1"))
+    except SQLAlchemyError:
+        db_ok = False
+    return {"status": "ok" if db_ok else "degraded", "db": "ok" if db_ok else "error"}