feat: implement 8 features across full stack

- Leaderboard: rank-based percentile tiers (champion/gold/silver/bronze),
    deterministic tie-breaking (xp DESC, user_id ASC)
  - Mentor chat: md: breakpoints, safe-area-inset-bottom padding
  - Learning progress: server-side progressPct, curriculum expansion safety
  - Physical orders: hard-disabled with 410 Gone
  - Certificate approval: pending/issued flow, admin issue/revoke endpoints,
    certificate_requires_approval setting (migration 0031)
  - Draft/publish: is_published on lessons and chapters, admin publish UI
    (migration 0030)
  - Video panel: static thumbnails (no preload), client-side pagination
  - Rich editor: TipTap + tiptap-markdown for lesson descriptions,
    marked + DOMPurify for SafeMarkdown rendering

frontend/src/components/admin/learning-panel.tsx

@@ -4,6 +4,7 @@ import { useEffect, useState } from "react";
 import { keepPreviousData, useQuery, useQueryClient } from "@tanstack/react-query";
 import {
   AlertTriangle,
+  Award,
   Flame,
   Heart,
   Loader2,
@@ -64,6 +65,7 @@ export function LearningPanel() {
   const [sort, setSort] = useState<SortKey>("xp");
   const [selectedId, setSelectedId] = useState<number | null>(null);
   const [unlocking, setUnlocking] = useState(false);
+  const [issuingCert, setIssuingCert] = useState(false);
   const [page, setPage] = useState(1);
 
   useEffect(() => {
@@ -114,6 +116,19 @@ export function LearningPanel() {
     }
   };
 
+  const issueCertificate = async (id: number) => {
+    setIssuingCert(true);
+    try {
+      await http.post(`/api/admin/users/${id}/certificate/issue`, {});
+      toast.success("گواهینامه با موفقیت صادر شد");
+      await qc.invalidateQueries({ queryKey: ["admin", "learning", "user", id] });
+    } catch (e) {
+      toast.error(toUserError(e, "صدور گواهینامه ممکن نشد"));
+    } finally {
+      setIssuingCert(false);
+    }
+  };
+
   const overview = overviewQ.data?.overview;
   const students = studentsQ.data?.items ?? [];
   const studentsTotal = studentsQ.data?.total ?? 0;
@@ -369,6 +384,25 @@ export function LearningPanel() {
                   ))}
                 </div>
 
+                {detailQ.data.learning.user.progressPct >= 100 && (
+                  <div className="flex items-center justify-between gap-3 rounded-xl border border-primary/30 bg-primary/5 px-3 py-2.5">
+                    <div className="flex items-center gap-2">
+                      <Award className="h-4 w-4 shrink-0 text-primary" />
+                      <p className="text-xs font-bold">دوره تکمیل شده — گواهینامه قابل صدور است</p>
+                    </div>
+                    <Button
+                      size="sm"
+                      variant="default"
+                      disabled={issuingCert}
+                      onClick={() => issueCertificate(detailQ.data!.learning.user.id)}
+                      className="gap-1.5"
+                    >
+                      {issuingCert ? <Loader2 className="h-3.5 w-3.5 animate-spin" /> : <Award className="h-3.5 w-3.5" />}
+                      صدور گواهینامه
+                    </Button>
+                  </div>
+                )}
+
                 <section className="space-y-2">
                   <h3 className="text-sm font-black">دروس</h3>
                   <div className="max-h-64 space-y-1.5 overflow-y-auto">