Add cross-site improvements across three phases

Phase 1 — Quick wins:
- Image lazy-loading on series/resource cards
- Newsletter signup added to Episodes page (before highlights)
- Per-route meta tags via usePageMeta hook (title, og:title, og:description)
- Breadcrumbs on study index, section, and notes pages
- SVG completion checkmark badges on study section list
- Analytics time-range filter (7d / 30d / 90d) in admin panel

Phase 2 — Medium features:
- Related episodes on archived series detail pages
- Resource library two-tier filter (type + tag chips)
- Global search (Fuse.js) moved below sticky header as full-width bar
- Q&A anonymous upvoting with localStorage dedup + admin pin/unpin
- Study enrollment funnel tracking (firstVisitAt, firstCompletionAt) with funnel chart in analytics

Phase 3 — Larger features:
- Study section comments (auto-approve for enrolled users, admin moderation panel)
- Study completion certificate (canvas render, PNG download, shareable public URL)
- Episode script full-text search (mammoth docx extraction, server-side search, admin upload UI)
- Reflection questions renamed from Discussion Questions; quiz answers can be shared to section discussion
- Public certificate route at /certificate/:token with og meta tags
- Comment moderation panel added to admin under Manage > Study Comments

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

src/components/QASection.tsx

@@ -8,6 +8,8 @@ interface PublicQuestion {
   topic?: string
   submittedAt?: string
   answeredAt?: string
+  upvotes?: number
+  pinned?: boolean
 }
 
 interface DecoratedQuestion extends PublicQuestion {
@@ -390,6 +392,12 @@ export default function QASection() {
   const [copiedQuestionId, setCopiedQuestionId] = useState<string | null>(null)
   const [copiedFacebookCaptionId, setCopiedFacebookCaptionId] = useState<string | null>(null)
   const [loading, setLoading] = useState(true)
+  const [votedIds, setVotedIds] = useState<Set<string>>(() => {
+    try {
+      const raw = localStorage.getItem('qa-voted-ids-v1')
+      return new Set(raw ? JSON.parse(raw) as string[] : [])
+    } catch { return new Set() }
+  })
   const resultsTopRef = useRef<HTMLDivElement | null>(null)
 
   useEffect(() => {
@@ -404,6 +412,22 @@ export default function QASection() {
       })
   }, [])
 
+  async function handleUpvote(id: string) {
+    if (votedIds.has(id)) return
+    try {
+      const res = await fetch(`/api/questions/${encodeURIComponent(id)}/upvote`, { method: 'POST' })
+      if (!res.ok) return
+      const data = await res.json() as { upvotes: number }
+      setQuestions(prev => prev.map(q => q.id === id ? { ...q, upvotes: data.upvotes } : q))
+      setVotedIds(prev => {
+        const next = new Set(prev)
+        next.add(id)
+        localStorage.setItem('qa-voted-ids-v1', JSON.stringify([...next]))
+        return next
+      })
+    } catch { /* ignore */ }
+  }
+
   useEffect(() => {
     setEngagement(readEngagementFromStorage())
   }, [])
@@ -839,22 +863,40 @@ export default function QASection() {
                         : question.answer
 
                       return (
-                        <article key={question.id} id={`qa-${question.id}`} className={`qa-card-scene${isFocused ? ' qa-card-scene--focused' : ''}`}>
+                        <article key={question.id} id={`qa-${question.id}`} className={`qa-card-scene${isFocused ? ' qa-card-scene--focused' : ''}${question.pinned ? ' qa-card-scene--pinned' : ''}`}>
                           <div className="qa-question-header">
                             <span className="qa-face-label">Q</span>
                             <span className="qa-question-main">
-                              <span className="qa-question-text">{renderHighlightedText(question.question, normalizedSearch)}</span>
+                              <span className="qa-question-text">
+                                {question.pinned && (
+                                  <span className="qa-pinned-badge" aria-label="Pinned question">📌 </span>
+                                )}
+                                {renderHighlightedText(question.question, normalizedSearch)}
+                              </span>
                               <span className="qa-question-meta">
                                 <span className="qa-topic-pill">{question._topic}</span>
                                 {formatDate(question.answeredAt ?? question.submittedAt) && (
                                   <span>{formatDate(question.answeredAt ?? question.submittedAt)}</span>
                                 )}
                                 {question._helpful > 0 && <span>{question._helpful} helpful</span>}
+                                {(question.upvotes ?? 0) > 0 && (
+                                  <span>👍 {question.upvotes}</span>
+                                )}
                               </span>
                             </span>
                           </div>
 
                           <div className="qa-card-actions">
+                            <button
+                              type="button"
+                              aria-label={votedIds.has(question.id) ? 'Already upvoted' : 'Upvote this question'}
+                              className={`qa-upvote-btn${votedIds.has(question.id) ? ' qa-upvote-btn--voted' : ''}`}
+                              onClick={() => handleUpvote(question.id)}
+                              disabled={votedIds.has(question.id)}
+                            >
+                              <svg viewBox="0 0 16 16" aria-hidden="true" fill="currentColor" width="13" height="13"><path d="M8 2L2 9h4v5h4V9h4z"/></svg>
+                              <span>{votedIds.has(question.id) ? 'Upvoted' : 'Upvote'}{(question.upvotes ?? 0) > 0 ? ` · ${question.upvotes}` : ''}</span>
+                            </button>
                             <button
                               type="button"
                               aria-label="Share on X"