sync: stale skill detection, sentry filtering, claim removal, review improvements

Stale Detection:
- Detect skills removed/moved from GitHub (3 consecutive 404s threshold)
- Hide stale skills from browse/search, show warning banner on detail page
- Serve cached files with isStale flag when GitHub returns 404
- Add stale-check crawler command for batch verification
- CLI shows warning when installing stale skills from cache

Sentry & Error Handling:
- Filter browser extension errors and add denyUrls
- Anti-inflation measures and sentinel recalibration for curation

Claim & Removal:
- Enhanced ClaimForm with repo-level removal support
- Add repo-removal-request API endpoint with tests
- Improved owner page with bilingual content

Review Pipeline:
- Review version and reviewer tracking in submit API
- Source format filter for pending reviews
- Updated review tests

Other:
- Updated i18n strings (en/fa)
- BrowseFilters improvements
- Dockerfile updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/app/[locale]/skill/[...id]/page.tsx

@@ -339,6 +339,33 @@ export default async function SkillPage({ params }: SkillPageProps) {
           </div>
         )}
 
+        {/* Stale Skill Warning Banner */}
+        {dbSkill.isStale && (
+          <div className="bg-warning/10 border-b border-warning/20">
+            <div className="container-main py-3">
+              <div className="flex items-start gap-3 text-sm">
+                <span className="text-warning text-lg flex-shrink-0">⚠</span>
+                <div>
+                  <p className="text-warning-foreground dark:text-warning" dir="auto">
+                    {isRTL
+                      ? 'این مهارت ممکن است از مخزن GitHub اصلی حذف یا جابجا شده باشد. فایل‌ها از حافظه پنهان SkillHub ارائه می‌شوند و ممکن است قدیمی باشند.'
+                      : 'This skill may have been removed or moved from its GitHub repository. Files are served from the SkillHub cache and may be outdated.'}
+                  </p>
+                  <a
+                    href={`https://github.com/${skill.author}/${skill.repo}`}
+                    target="_blank"
+                    rel="noopener noreferrer"
+                    className="inline-flex items-center gap-1 mt-1 text-primary-600 hover:text-primary-700 dark:text-primary-400 dark:hover:text-primary-300 font-medium"
+                  >
+                    {isRTL ? 'بررسی مخزن GitHub' : 'Check GitHub repository'}
+                    <ExternalLink className="w-3 h-3" />
+                  </a>
+                </div>
+              </div>
+            </div>
+          </div>
+        )}
+
         {/* Stats Bar */}
         <div className="bg-surface-elevated border-b border-border">
           <div className="container-main">