test(qa-callers): hand the caller phase its invocation-start observations and review token; fix(next-version): fetch without auto maintenance

- Every caller case receives the diff, status, log, untracked list, HEAD and an
  already-captured review start token, so the phase spends its budget on the
  contract under test instead of re-running setup reads.
- gstack-next-version's fetches pass --no-auto-maintenance. On git 2.55 a
  completed fetch forks detached maintenance in the caller's repository; the
  free suite's live smoke test ran it inside the CI checkout, and every
  shard-12 pre-push hook hang so far followed a completed smoke fetch.

bin/gstack-next-version

@@ -165,7 +165,7 @@ function zeroBaseAtLocalWidth(versionPath: string, repoRoot: string): string {
 function readBaseVersion(base: string, versionPath: string, repoRoot: string, warnings: string[]): string {
   // git fetch is best-effort; we tolerate failure and fall back to whatever
   // origin/<base> currently points at.
-  runCommand("git", ["fetch", "origin", base, "--quiet"], 10000);
+  runCommand("git", ["fetch", "--no-auto-maintenance", "origin", base, "--quiet"], 10000);
   const r = runCommand("git", ["show", `origin/${base}:${versionPath}`]);
   if (!r.ok) {
     const assumed = zeroBaseAtLocalWidth(versionPath, repoRoot);
@@ -610,7 +610,7 @@ function fetchGitClaimed(
     // bounded) brings every missing tip local in a single round trip.
     spawnSync(
       "git",
-      ["fetch", "origin", ...pending.map((p) => `refs/heads/${p.branch}`), "--depth=1", "--no-tags"],
+      ["fetch", "--no-auto-maintenance", "origin", ...pending.map((p) => `refs/heads/${p.branch}`), "--depth=1", "--no-tags"],
       { encoding: "utf8", timeout: 15000, env: { ...process.env, GIT_TERMINAL_PROMPT: "0" } },
     );
     // One unservable ref (dangling sha on the server) fails the WHOLE batch
@@ -626,7 +626,7 @@ function fetchGitClaimed(
         retries++;
         spawnSync(
           "git",
-          ["fetch", "origin", `refs/heads/${branch}`, "--depth=1", "--no-tags"],
+          ["fetch", "--no-auto-maintenance", "origin", `refs/heads/${branch}`, "--depth=1", "--no-tags"],
           { encoding: "utf8", timeout: 5000, env: { ...process.env, GIT_TERMINAL_PROMPT: "0" } },
         );
         outcome = readClaim(branch, sha);