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/redact.py

@@ -0,0 +1,42 @@
+"""Defense-in-depth redaction of secret-like material.
+
+This is a backstop, not the primary control. The primary control is that secret
+values are never passed into evidence/log code paths in the first place. Redaction
+catches the case where a value leaks into child-process output we control.
+"""
+from __future__ import annotations
+
+import re
+from typing import Iterable
+
+REDACTED = "***REDACTED***"
+
+# Token shapes we proactively mask in child-process output.
+_PATTERNS = [
+    re.compile(r"npm_[A-Za-z0-9]{8,}"),          # npm automation/publish tokens
+    re.compile(r"(?:hv|hvs|hvb|s)\.[A-Za-z0-9._-]{16,}"),  # vault/openbao tokens
+    re.compile(r"gh[pousr]_[A-Za-z0-9]{16,}"),    # github tokens
+    re.compile(r"xox[baprs]-[A-Za-z0-9-]{10,}"),  # slack tokens
+    re.compile(r"AKIA[0-9A-Z]{16}"),              # aws access key id
+]
+
+
+def redact_text(text: str, extra: Iterable[str] = ()) -> str:
+    """Mask known token shapes and any caller-supplied literal values."""
+    if not text:
+        return text
+    for literal in extra:
+        if literal and len(literal) >= 4:
+            text = text.replace(literal, REDACTED)
+    for pat in _PATTERNS:
+        text = pat.sub(REDACTED, text)
+    return text
+
+
+def looks_secret(name: str) -> bool:
+    """Heuristic: does a field/key name suggest it carries a secret value?"""
+    lowered = name.lower()
+    return any(
+        marker in lowered
+        for marker in ("token", "secret", "password", "passwd", "apikey", "api_key", "key", "credential")
+    )