fix: review hardening — full push-range diff, fail-closed diff fetch, crash-safe queue, 403 self-heal

- push reviews now fetch ONE compare diff (before...after) instead of
  slicing to the first 20 commits under a head-sha status; new-branch
  pushes (zero before-sha) fall back to the head commit diff
- truncated diffs can no longer yield a clean pass: verdict capped at
  warn and status description prefixed 'partial review (diff truncated)'
- any diff-fetch failure (throw / empty body on a non-empty push or PR)
  short-circuits to status 'warning' ('review unavailable — diff fetch
  failed (not blocking)') with a ledger row; a diffless prompt is never
  sent to the model
- accepted jobs persist to sqlite (queue_jobs) before the pending status
  posts; startup re-enqueues rows that never reached a final state, so
  restarts no longer strand shas at 'pending'
- 403 on status/comment posts self-heals: admin-scoped token (config
  admin_token) adds shre-reviewer as collaborator (write), retries once
- scripts/wire-repos.mjs: idempotent estate-wide webhook + collaborator
  wiring over GET /repos/search
- tests: 32 -> 51 (truncation cap, persisted-queue reconciliation,
  collab-retry stubs, fetchDiff routing)

Co-Authored-By: Claude Fable 5 <[email protected]>

src/lib/verdict.js

@@ -62,6 +62,13 @@ export function normalizeReview(raw) {
   return review;
 }
 
+// A truncated diff means part of the change was never reviewed: a clean
+// 'pass' cannot be claimed. Cap at 'warn'; a confirmed-critical 'fail' stands.
+export function applyTruncationCap(review, truncated) {
+  if (truncated && review && review.verdict === 'pass') review.verdict = 'warn';
+  return review;
+}
+
 function clampScore(v) {
   const n = Number(v);
   if (!Number.isFinite(n)) return 0;