fix: adversarial review fixes (Claude + Codex cross-model passes)

Both adversarial passes ran against the wave; every FIXABLE finding landed
with a regression test:

- probeTimeoutMs clamps to >=1ms: a fractional override floored to 0, and
  execFileSync treats timeout:0 as NO timeout — the probe that exists to
  bound hangs could hang forever (found by both models independently).
- /ship silent hook install now requires the hooks dir to live inside
  .git: with core.hooksPath (husky's COMMITTED .husky/), the chaining
  installer would have renamed the team's committed pre-push and written a
  machine-local wrapper into the working tree (found by both models).
- gstack-config gbrain-refresh accepts the "timeout" status — the last
  consumer still gating on literal "ok" (Codex); gstack-gbrain-detect's
  config-derived fields honor GBRAIN_HOME so the detection JSON can't
  report status ok alongside config_exists false (Codex).
- prepush: a remote sha absent locally (shallow clone / stale fetch) falls
  back to the merge-base/empty-tree range — scans MORE, never blocks a
  legitimate push into training users toward --no-verify.
- dashboards: curl's own 000 no longer doubles to "HTTP 000000"; the
  community dashboard flags stale snapshots like the security one; array
  sections parse via jq (the sed/grep loops truncated at the first ']');
  the no-jq marker grep tolerates whitespace.
- telemetry: multi-line redactor output nulls the field instead of
  corrupting the JSONL record; setup's hint fires only when the config key
  is genuinely unset (an explicit false is a recorded decline); the /ship
  prompt marker honors GSTACK_HOME.

Kept as designed (cross-model tension noted): Bearer stays MEDIUM in the
prepush gate — a HIGH Bearer would block every docs example; the entropy
validator can't eliminate that FP class, and MEDIUM warns visibly.

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

test/redact-prepush-hook.test.ts

@@ -128,6 +128,19 @@ describe("fail closed on unscannable diffs (#1946)", () => {
     expect(code).toBe(0);
   });
 
+  test("a remote sha absent locally (shallow clone / stale fetch) falls back to scanning MORE, not blocking", () => {
+    // Adversarial review finding 8: remote..local can't resolve when the
+    // remote tip object isn't in the local odb. The fallback scans the
+    // merge-base/empty-tree range — a secret in the pushed content still
+    // blocks; a clean push passes instead of hard-failing.
+    const fakeRemoteSha = "c".repeat(40);
+    const head = commit("secrets.txt", "key AKIA1234567890ABCDEF\n", "leaky commit");
+    const { code, stderr } = runHook(`refs/heads/main ${head} refs/heads/main ${fakeRemoteSha}\n`);
+    expect(code).toBe(1); // fallback range still catches the credential
+    expect(stderr).toContain("aws.access_key");
+    expect(stderr).not.toContain("could not compute the pushed diff");
+  });
+
   test("a diff killed by a signal (null status — the maxBuffer/kill class) BLOCKS", () => {
     // Stub git: probes delegate to the real git; the diff invocation kills
     // itself, producing spawnSync status === null. This is the exact branch