fix: pre-landing review fixes

Review army findings (1 critical, auto-fixed with regression tests):

- CRITICAL (security specialist, verified live): redactFindingSpans spliced
  only the regex capture span, and pem.private_key / gcp.service_account
  capture just the BEGIN-header — the key body survived "redaction" and
  shipped via telemetry. Marker-only patterns now drop the whole payload
  (null, fail closed). Overlapping spans (Bearer+JWT on the same bytes) are
  coalesced before splicing so stale offsets can't leave partial secret
  bytes behind.
- gitStrict: drop the dead `|| r.status === null` disjunct (null !== 0
  already covers it); add the signal-kill/null-status regression test the
  docstring promised.
- security-dashboard human mode flags stale snapshots ("figures may be out
  of date") instead of presenting frozen counts as current.
- community-dashboard marker check uses jq when available — the grep-only
  variant misclassified whitespaced/reserialized bodies as legacy.
- telemetry fail-closed test now shadows bun with a failing stub
  (deterministic on any host layout); stale "five status cases" describe
  title renamed.

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

bin/gstack-redact-prepush

@@ -54,7 +54,9 @@ function git(args: string[]): string {
  */
 function gitStrict(args: string[]): string {
   const r = spawnSync("git", args, { encoding: "utf8", maxBuffer: 64 * 1024 * 1024 });
-  if (r.status !== 0 || r.status === null) {
+  // status !== 0 covers BOTH a non-zero exit AND null (process killed by a
+  // signal or maxBuffer overflow — null !== 0 is true).
+  if (r.status !== 0) {
     throw new Error(
       `git ${args[0]} failed (status=${r.status ?? "killed/overflow"}): ${(r.stderr ?? "").slice(0, 300)}`,
     );