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/gbrain-local-status.test.ts

@@ -297,6 +297,11 @@ describe("probeTimeoutMs — env override parsing", () => {
     expect(probeTimeoutMs({ GSTACK_GBRAIN_PROBE_TIMEOUT_MS: "0" })).toBe(DEFAULT_PROBE_TIMEOUT_MS);
     expect(probeTimeoutMs({ GSTACK_GBRAIN_PROBE_TIMEOUT_MS: "-5" })).toBe(DEFAULT_PROBE_TIMEOUT_MS);
   });
+
+  it("never returns 0 for fractional sub-millisecond values (0 = NO timeout in execFileSync)", () => {
+    expect(probeTimeoutMs({ GSTACK_GBRAIN_PROBE_TIMEOUT_MS: "0.5" })).toBe(1);
+    expect(probeTimeoutMs({ GSTACK_GBRAIN_PROBE_TIMEOUT_MS: "0.0001" })).toBe(1);
+  });
 });
 
 describe("lib/gbrain-local-status — cache behavior", () => {