feat(curator): vendor the application backend as the scenario's tracked source

The curator Python backend (package, tests, systemd units, config templates, scripts) now lives under scenarios/curator/backend and is the single source of truth; the live checkout at the workspace path is a runtime copy. Exported from the app repo's tracked tree via git archive (no history, .pi/venv/caches excluded). 149 unit tests pass from the new location.

profile.toml backend is now repo-relative (scenarios/curator/backend); verify-generated.sh resolves a relative backend against REPO_ROOT. verify-no-secrets ASSIGN heuristic now requires value entropy so vendored kwargs like token=extraction_token no longer false-positive. README documents the backend/ layout and the operator-owned app rollout step.

scenarios/curator/backend/pyproject.toml

@@ -0,0 +1,16 @@
+[project]
+name = "curator-media-library"
+version = "0.1.0"
+description = "LAN-first personal book, film, TV and music curation service"
+requires-python = ">=3.12"
+
+[project.scripts]
+curator = "curator.cli:main"
+
+[build-system]
+requires = ["setuptools>=75"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools]
+packages = ["curator"]
+