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>

docs/ops-warden-routing-contract.md

@@ -0,0 +1,62 @@
+# ops-warden → secrets-engine Routing Contract
+
+ops-warden issues **SSH certificates only**. Every other credential need (API
+keys, provider tokens, DB passwords, npm publish tokens) routes to
+**secrets-engine**, which is OpenBao-backed. ops-warden must never request, hold,
+cache, or vend a raw secret value. A route result is a **pointer**, not a key.
+
+## What ops-warden calls
+
+```bash
+secrets-engine route <catalog-id> --json
+```
+
+## What it returns (the contract)
+
+```json
+{
+  "catalog_id":       "whynot-design-npm-publish",
+  "owner":            "whynot-design",
+  "stage":            "prod",
+  "decision_status":  "resolved",
+  "decision_ref":     "whynot-design-npm-publish",
+  "review_url":       "http://127.0.0.1:8000/decisions/<id>",
+  "metadata_applied": true,
+  "value_present":    true,
+  "ready":            true,
+  "next_command":     "secrets-engine exec --catalog whynot-design-npm-publish -- <command...>",
+  "missing":          ""
+}
+```
+
+| Field | Meaning |
+| --- | --- |
+| `decision_status` | `resolved`/`approved` => approved; `missing`/`pending` => not yet |
+| `metadata_applied` | OpenBao ACL policy + approle exist for the lane |
+| `value_present` | the secret value has been provisioned (boolean only — value never read) |
+| `ready` | approved **and** applied **and** provisioned |
+| `next_command` | the single safe command the caller should run next |
+| `missing` | the one human/provisioning step still outstanding |
+
+## Guarantees
+
+- **No value crosses this boundary.** `route` reports a boolean `value_present`,
+  derived from a metadata/presence check — it never reads the secret.
+- **Actionable when not ready.** If a lane is unapproved, unapplied, or
+  unprovisioned, `next_command` + `missing` tell the caller exactly what to do.
+- **Idempotent / read-only.** `route` performs no mutation.
+
+## whynot-design retry flow
+
+1. whynot-design CI needs a publish token → asks ops-warden.
+2. ops-warden runs `secrets-engine route whynot-design-npm-publish --json`.
+3. If `ready=false`, it surfaces `missing` + `next_command` to the human (e.g.
+   "needs approved decision" or "needs provisioning").
+4. Once `ready=true`, the workload runs
+   `secrets-engine exec --catalog whynot-design-npm-publish -- npm publish`.
+
+## Anti-patterns (forbidden)
+
+- ops-warden `POST /messages/` asking for `NPM_TOKEN` / `OPENROUTER_API_KEY`.
+- Caching `value_present` as if it were the value.
+- Inventing `warden secret` / `warden bao` — they do not exist.