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>

src/secrets_engine/apply.py

@@ -0,0 +1,69 @@
+"""Apply a guarded plan to OpenBao. Idempotent and decision-gated.
+
+Apply only ever writes *metadata* (KV mount, ACL policy, approle role). It does
+NOT write secret values — that is the separate, more constrained `provision` step.
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from secrets_engine.catalog import CatalogEntry
+from secrets_engine.openbao import OpenBaoClient
+from secrets_engine.plan import Plan
+
+
+@dataclass
+class ApplyResult:
+    applied: list[str]
+    skipped: list[str]
+
+    def render(self) -> str:
+        out = []
+        for a in self.applied:
+            out.append(f"  applied: {a}")
+        for s in self.skipped:
+            out.append(f"  unchanged: {s}")
+        return "\n".join(out) or "  (nothing to do)"
+
+
+def apply_plan(client: OpenBaoClient, entry: CatalogEntry, plan: Plan, ttl: str = "30m") -> ApplyResult:
+    """Execute the plan's metadata actions idempotently.
+
+    Idempotency: KV mount and approle are enable-if-absent; the policy is written
+    only when its current body differs from the desired HCL.
+    """
+    applied: list[str] = []
+    skipped: list[str] = []
+
+    # 1. KV mount.
+    if client.kv_mount_exists(entry.mount):
+        skipped.append(f"kv-mount {entry.mount} (already present)")
+    else:
+        client.ensure_kv_mount(entry.mount)
+        applied.append(f"kv-mount {entry.mount}")
+
+    # 2. Consumer ACL policy (write only if changed).
+    current = client.read_policy(plan.policy_name)
+    if current and _normalize(current) == _normalize(plan.policy_hcl):
+        skipped.append(f"policy {plan.policy_name} (unchanged)")
+    else:
+        client.write_policy(plan.policy_name, plan.policy_hcl)
+        applied.append(f"policy {plan.policy_name}")
+
+    # 3. Consumer approle bound to that policy.
+    client.ensure_approle_enabled()
+    client.write_approle(plan.role_name, [plan.policy_name], ttl=ttl)
+    applied.append(f"approle {plan.role_name} -> [{plan.policy_name}]")
+
+    return ApplyResult(applied=applied, skipped=skipped)
+
+
+def _normalize(hcl: str) -> str:
+    """Compare policy bodies ignoring comments and whitespace noise."""
+    lines = []
+    for raw in hcl.splitlines():
+        line = raw.strip()
+        if not line or line.startswith("#"):
+            continue
+        lines.append(" ".join(line.split()))
+    return "\n".join(lines)