Implement v1 URL shortener (Bearer API, public 302, landing, CI) (#2)

## Summary

- Standalone Django 6 shortener: Bearer `/api/links/` (create/list/detail/disable) and public `GET /<code>` 302
- Host split, target-host allowlist, named rotatable tokens; `short_url` from `PUBLIC_SHORT_URL`
- Landing page, DEBUG-only `/debug/` mint form, Django admin
- Docker/compose (host **8005**), Gitea CI like monica_site (PR tests, beta on merge, prod button)
- Caller contract in `API.md`

Closes #1. Infra follow-up: [server-infra#22](ai_ml_operations/server-infra#22).

## Test plan
- [ ] `cd site && uv run python manage.py test`
- [ ] `docker compose up --build` → http://127.0.0.1:8005/
- [ ] `POST /api/links/` with `Bearer monica:dev-only-token` → 201
- [ ] `GET /<code>` → 302 to allowlisted https URL
- [ ] No Bearer → 401; non-allowlisted host → 400
- [ ] `/debug/` only when `DEBUG=true`

Reviewed-on: #2

pyproject.toml

@@ -0,0 +1,15 @@
+[project]
+name = "url-shortening-service"
+version = "0.1.0"
+description = "Django URL shortener for MKDRealtor / monica_site"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = [
+    "django>=6.0,<7",
+    "gunicorn>=23.0.0",
+    "psycopg[binary]>=3.3.3",
+    "whitenoise>=6.9.0",
+]
+
+[tool.uv]
+package = false