feat(ci): supply-chain hygiene — secret gate on every PR diff, dependency review, OSV, dependabot, evidence-bar PR template

The repo owned a redaction engine and had zero CI-side secret scanning.
quality-gate.yml now pipes every PR diff's ADDED lines through our own
bin/gstack-redact (gate-secret-scan.mjs, taken from the fork — it dogfoods
the engine): HIGH findings fail the check, MEDIUM prints an advisory count
only (no human in CI to confirm), planted-bug fixtures excluded by pathspec.
Live-verified both directions: PEM key fails, clean diff and MEDIUM shapes
pass; ShellCheck (errors) covers the setup/build shell boundary and passes
today; bun audit gates critical advisories. Trigger is pull_request, never
pull_request_target.

dependency-review.yml adopts the hardened never-merged prior-art branch
(fail-on-severity high, workflow paths watched, tight perms) — verify the
dependency graph parses bun.lock with a canary bump before trusting the
gate. dependabot: weekly, grouped per ecosystem, capped PR counts; and
evals.yml image build/push now skips dependabot actors, whose read-only
GITHUB_TOKEN made every lockfile bump a permanently red check. OSV scans
weekly with a reasoned ignore file. All new workflow actions SHA-pinned.
Scorecard deliberately not taken (no consumer for the score).

The PR template front-loads the evidence bar (live proof, liveness
screenshot, no-ETHOS/voice-changes checklist); the unenforced DCO line is
dropped. bin/gstack-verify-gate ships OPT-IN (never registered by ./setup —
a Stop hook running the project's verify command after every turn is the
user's call), with the fork's tests adapted to pin exactly that.

Ported from time-attack/gstack (GStack 2) + our own prior-art branch.

Co-authored-by: Sina Matian <sina@time-attack.dev>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.osv-scanner.toml

@@ -0,0 +1,15 @@
+# OSV-Scanner configuration.
+# Direct/transitive dependency versions are pinned to their fixed releases via
+# the `overrides` block in package.json; this file only records advisories we
+# have assessed as not-reachable or not-fixable without disproportionate risk.
+
+[[IgnoredVulns]]
+id = "GHSA-frvp-7c67-39w9"
+# @hono/node-server 1.19.x. Reachable only through @modelcontextprotocol/sdk,
+# which is an unused transitive dependency (no source file imports it) and never
+# starts a Hono HTTP server, so the advisory's request path is not exercised.
+# The only fix is @hono/node-server 2.0.5, a major bump the MCP SDK pins against
+# (^1.19.9); forcing it via override risks breaking the SDK at runtime for a
+# vulnerability we do not expose. Re-evaluate if the MCP SDK becomes a direct,
+# server-hosting dependency.
+reason = "Unreachable transitive (unused @modelcontextprotocol/sdk); fix requires a risky major override on a pinned peer dep."