feat(frontend): draft/publish, certificate approval UI, contributors, leaderboard tiers

- admin-studio: chapter/lesson publish toggle with Draft/Published badges; per-chapter accordion
- cap/page: remove auto-issue effect; student requests, admin approves
- learning-panel: admin issue-certificate action per student
- site-settings: contributors editor with avatar upload (ContributorAvatarPicker, TagInput)
- community-panel: render contributors section below social links
- leaderboard-panel: TierBadge, totalParticipants, tier on entries and self
- page.tsx: fix "شروع مسیر" routing to /register instead of /login
- navbar: correct icons (Settings, Palette) in user dropdown
- types: Contributor, LeaderboardTier, Certificate status field, updated LeaderboardData/Entry
- layout: PWA icon metadata (192, 512, apple-touch-icon)

frontend/src/app/cap/page.tsx

@@ -73,13 +73,6 @@ function CapPageInner() {
     enabled: !!user && curriculumDone,
   });
 
-  useEffect(() => {
-    if (!curriculumDone || !user) return;
-    void http
-      .post("/api/me/certificate/issue", {})
-      .then(() => qc.invalidateQueries({ queryKey: ["me", "certificate"] }))
-      .catch((e) => toast.error(toUserError(e, "صدور گواهینامه ممکن نشد")));
-  }, [curriculumDone, user, qc]);
 
   if (isLoading) {
     return <CapSkeleton />;