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/gitea.js

@@ -41,6 +41,20 @@ export class GiteaClient {
     return this.req('GET', `/api/v1/repos/${owner}/${repo}/compare/${before}...${after}`);
   }
 
+  // Full-range diff for a push (base...head) in ONE request. Gitea 1.27's API
+  // has no compare .diff variant, but the web compare route serves .diff and
+  // accepts `Authorization: token` (verified live on 1.27.1).
+  getCompareDiff(owner, repo, before, after) {
+    return this.req('GET', `/${owner}/${repo}/compare/${before}...${after}.diff`, { raw: true });
+  }
+
+  // Add a collaborator (requires owner/admin token). 204 on success.
+  addCollaborator(owner, repo, username, permission = 'write') {
+    return this.req('PUT', `/api/v1/repos/${owner}/${repo}/collaborators/${username}`, {
+      body: { permission }, ok: [204]
+    });
+  }
+
   // File content at HEAD (returns null when absent)
   async getFileHead(owner, repo, path, maxBytes = 8192) {
     try {