feat(mvp): working secrets-engine CLI for the whynot-design npm publish lane

Implements SECRETS-WP-0002 end to end as a uv-managed Python package:

- catalog: non-secret lane registry + strict validator (build/test/prod)
- stage roles + OpenBao ACL policies; guards refuse wildcards, sys/, identity/,
  admin names, and cross-stage paths before any backend call
- plan/apply: dry-run-first, idempotent policy + approle apply, decision-gated
- decisions: State Hub lookup with local-fixture fallback; non-secret evidence
  to JSONL + hub progress, scrubbed of any value
- provision/verify: mode-0600 file import + generated test values; positive/
  negative checks that never print the value
- exec delivery: `exec --catalog ... -- npm publish` injects the token via a
  temp .npmrc for the child only, cleaned up on exit/failure/interrupt
- ops-warden routing contract + hardening backlog docs
- 34 tests incl. live OpenBao integration; scripts/demo-e2e.sh runs the full
  chain against a throwaway bao dev server

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,30 @@
+[project]
+name = "secrets-engine"
+version = "0.1.0"
+description = "Decision-aware workflow and automation layer for approved secret custody, delivery, and lifecycle work, backed by OpenBao."
+readme = "README.md"
+requires-python = ">=3.11"
+license = { text = "see LICENSE" }
+authors = [{ name = "NetKingdom / Custodian" }]
+dependencies = [
+  "PyYAML>=6.0",
+]
+
+[project.optional-dependencies]
+dev = [
+  "pytest>=7.4",
+]
+
+[project.scripts]
+secrets-engine = "secrets_engine.cli:main"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/secrets_engine"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+addopts = "-q"