Add a newsletter archive so past issues can be shared and found; v2.3.0

Web-hosted copies of episode newsletters, published from Resend broadcasts
tagged with the "New Episode" topic. Gives Facebook (and anyone else) a
proper link to share instead of raw HTML email, and makes issues findable
via site search and Google.

- Admin "Newsletter Archive" tab lists sent Resend broadcasts, flags ones
  tagged "New Episode", and publishes them with one click (pulls the HTML
  straight from Resend's API)
- Public /newsletter archive index and /newsletter/:slug issue pages,
  server-rendered with per-issue Open Graph tags for social previews
- Unsubscribe merge-tag stripped from the web copy; archive + subscribe
  links appended
- Issues added to sitemap.xml and the on-site search index

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/hooks/useGlobalSearch.ts

@@ -2,7 +2,7 @@ import { useMemo, useState, useEffect, useRef } from 'react'
 import Fuse from 'fuse.js'
 import type { SiteContent } from '../content'
 
-export type SearchResultType = 'episode' | 'question' | 'resource' | 'series'
+export type SearchResultType = 'episode' | 'question' | 'resource' | 'series' | 'newsletter'
 
 export interface SearchResult {
   id: string
@@ -37,6 +37,7 @@ export function useGlobalSearch(content: SiteContent) {
   const [questions, setQuestions] = useState<PublicQuestion[]>([])
   const [episodeItems, setEpisodeItems] = useState<SearchResult[]>([])
   const [nuggetsItems, setNuggetsItems] = useState<SearchResult[]>([])
+  const [newsletterItems, setNewsletterItems] = useState<SearchResult[]>([])
   const [scriptResults, setScriptResults] = useState<SearchResult[]>([])
   const scriptDebounceRef = useRef<ReturnType<typeof setTimeout> | null>(null)
 
@@ -95,6 +96,24 @@ export function useGlobalSearch(content: SiteContent) {
       .catch(() => {})
   }, [])
 
+  // Fetch published newsletter issues once on mount
+  useEffect(() => {
+    fetch('/api/newsletter/issues')
+      .then(r => r.ok ? r.json() : Promise.reject())
+      .then((data: { issues?: Array<{ id: string; slug: string; title: string; description?: string; sentAt?: string | null }> }) => {
+        const items: SearchResult[] = (data.issues ?? []).map(issue => ({
+          id: `newsletter-${issue.id}`,
+          type: 'newsletter' as const,
+          title: issue.title,
+          subtitle: 'Newsletter',
+          description: issue.description,
+          href: `/newsletter/${issue.slug}`,
+        }))
+        setNewsletterItems(items)
+      })
+      .catch(() => {})
+  }, [])
+
   // Season number → book/study title, so script results can show "Romans" instead of "Season 3"
   const seasonTitleMap = useMemo(() => {
     const map = new Map<string, string>()
@@ -164,7 +183,7 @@ export function useGlobalSearch(content: SiteContent) {
     return results
   }, [content, questions])
 
-  const allFuseItems = useMemo(() => [...episodeItems, ...nuggetsItems, ...staticItems], [episodeItems, nuggetsItems, staticItems])
+  const allFuseItems = useMemo(() => [...episodeItems, ...nuggetsItems, ...newsletterItems, ...staticItems], [episodeItems, nuggetsItems, newsletterItems, staticItems])
 
   const fuse = useMemo(() => new Fuse(allFuseItems, {
     keys: [