fix: sweep wave 3 — the execFileSync family gets timeouts (90 sites, 17 files)

The tripwire's regex covered spawnSync/execSync/Bun.spawnSync but not
execFileSync — an entire blocking sync-spawn API family that could
reintroduce the shard-wedge class undetected (ship review army). Same
mechanical recipe as waves 1-2: timeout: 30_000 default, 120_000 for slow
ops, shared wrappers fixed once, string-needle sites skipped with reasons.

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

test/gbrain-local-status.test.ts

@@ -210,6 +210,7 @@ describe("lib/gbrain-local-status — status classification", () => {
     );
 
     expect(source).not.toContain('command -v gbrain');
+    // tripwire-exempt: string assertion on lib source text, not a call
     expect(source).toContain('execFileSync("gbrain", ["--version"]');
   });