feat(redact): six new credential patterns — GitLab, HuggingFace, npm, DigitalOcean, Bearer, GCP SA (#1946)

Coverage gaps from the #1946 security review, including token types for
tooling gstack itself drives (glab):

HIGH (block): gitlab.token (glpat-/glptt-/gldt-), huggingface.token (hf_),
npm.token (npm_), digitalocean.token (dop_v1_), gcp.service_account (the
JSON-escaped "private_key" form that dodges pem.private_key's literal-block
match when minified, confirmed by "private_key_id" proximity).

MEDIUM (warn): auth.bearer — the most FP-prone shape in the set (docs are
full of "Authorization: Bearer <token>"), so it requires header-context
proximity and the same entropy>=3.0 + placeholder validator recipe as
env.kv. "Bearer YOUR_TOKEN_HERE" never fires; calibration over coverage,
per the cries-wolf principle.

All shapes are linear-time; test/redact-pattern-lint.test.ts covers them
automatically. Engine tests add positive + placeholder-negative cases per
pattern.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/redact-patterns.ts

@@ -222,6 +222,48 @@ export const PATTERNS: RedactPattern[] = [
     description: "GitHub fine-grained PAT",
     regex: /\b(github_pat_[A-Za-z0-9_]{82})\b/,
   },
+  {
+    id: "gitlab.token",
+    tier: "HIGH",
+    category: "secret",
+    description: "GitLab token (personal/pipeline-trigger/deploy)",
+    // glpat- personal access, glptt- pipeline trigger, gldt- deploy token.
+    // gstack drives glab first-class — these were a coverage gap (#1946).
+    regex: /\b(gl(?:pat|ptt|dt)-[A-Za-z0-9_-]{20,})\b/,
+  },
+  {
+    id: "huggingface.token",
+    tier: "HIGH",
+    category: "secret",
+    description: "HuggingFace access token",
+    regex: /\b(hf_[A-Za-z0-9]{30,})\b/,
+  },
+  {
+    id: "npm.token",
+    tier: "HIGH",
+    category: "secret",
+    description: "npm granular access token",
+    regex: /\b(npm_[A-Za-z0-9]{36})\b/,
+  },
+  {
+    id: "digitalocean.token",
+    tier: "HIGH",
+    category: "secret",
+    description: "DigitalOcean personal access token",
+    regex: /\b(dop_v1_[a-f0-9]{64})\b/,
+  },
+  {
+    id: "gcp.service_account",
+    tier: "HIGH",
+    category: "secret",
+    description: "GCP service-account JSON private key",
+    // The JSON-escaped form ("private_key": "-----BEGIN PRIVATE KEY-----\n...)
+    // dodges pem.private_key's literal-block match when minified to one line.
+    // Proximity to "private_key_id" confirms the GCP service-account shape.
+    regex: /("private_key"\s*:\s*"-----BEGIN (?:RSA |EC )?PRIVATE KEY-----)/,
+    nearRegex: /"private_key_id"/,
+    nearWindow: 300,
+  },
   {
     id: "anthropic.key",
     tier: "HIGH",
@@ -352,6 +394,22 @@ export const PATTERNS: RedactPattern[] = [
       !/^\$\{?[A-Za-z_]/.test(span) &&
       shannonEntropy(span) >= 3.0,
   },
+  {
+    id: "auth.bearer",
+    tier: "MEDIUM",
+    category: "secret",
+    description: "Authorization Bearer token (high-entropy, header context)",
+    // FP-prone shape (docs and examples are full of "Bearer <token>"), so:
+    // MEDIUM tier, requires "authorization" nearby, and the same entropy
+    // recipe as env.kv to kill Bearer YOUR_TOKEN_HERE placeholders.
+    regex: /\bBearer[ \t]+([A-Za-z0-9._~+/=-]{20,})\b/,
+    nearRegex: /authorization/i,
+    nearWindow: 80,
+    validate: (span) =>
+      !isPlaceholderSpan(span) &&
+      !/^\$\{?[A-Za-z_]/.test(span) &&
+      shannonEntropy(span) >= 3.0,
+  },
 
   // ===== MEDIUM — PII (auto-redactable subset) =====
   {