refactor: simplify OG fetch - remove timeout wrapper and background refresh

Remove Promise.race timeout wrapper and let relay fetch use its natural
timeouts (7s for article, 5s for profile). Remove background refresh
complexity entirely.

Flow is now simple:
1. Check Redis cache
2. If miss, fetch from relays (up to 7s)
3. Cache result
4. Subsequent requests hit cache

First request may take 7-8 seconds, but after that it's cached and fast.
Much simpler and more reliable.

api/article-og.ts

@@ -28,17 +28,11 @@ export default async function handler(req: VercelRequest, res: VercelResponse) {
   let cacheMaxAge = 86400
 
   if (!meta) {
-    // Cache miss: try relays with short timeout
+    // Cache miss: fetch from relays (let it use its natural timeouts)
     console.log(`Cache miss for ${naddr}, fetching from relays...`)
     
     try {
-      // Fetch with 5 second timeout (relays can be slow)
-      const relayPromise = fetchArticleMetadataViaRelays(naddr)
-      const timeoutPromise = new Promise<null>((resolve) => {
-        setTimeout(() => resolve(null), 5000)
-      })
-      
-      meta = await Promise.race([relayPromise, timeoutPromise])
+      meta = await fetchArticleMetadataViaRelays(naddr)
       
       if (meta) {
         console.log(`Relays found metadata for ${naddr}:`, { title: meta.title, summary: meta.summary?.substring(0, 50) })
@@ -48,8 +42,8 @@ export default async function handler(req: VercelRequest, res: VercelResponse) {
         })
         cacheMaxAge = 86400
       } else {
-        console.log(`Relay fetch timeout/failed for ${naddr}, using default fallback`)
-        // Relay fetch failed or timed out: use default fallback
+        console.log(`Relay fetch failed for ${naddr}, using default fallback`)
+        // Relay fetch failed: use default fallback
         cacheMaxAge = 300
       }
     } catch (err) {
@@ -60,34 +54,6 @@ export default async function handler(req: VercelRequest, res: VercelResponse) {
     console.log(`Cache hit for ${naddr}:`, { title: meta.title, summary: meta.summary?.substring(0, 50) })
   }
 
-  // Trigger background refresh on cache miss (fire-and-forget)
-  if (!meta) {
-    const secret = process.env.OG_REFRESH_SECRET || ''
-    const origin = req.headers['x-forwarded-proto'] && req.headers['x-forwarded-host']
-      ? `${req.headers['x-forwarded-proto']}://${req.headers['x-forwarded-host']}`
-      : `https://read.withboris.com`
-    
-    const refreshUrl = `${origin}/api/article-og-refresh?naddr=${encodeURIComponent(naddr)}`
-    console.log(`Triggering background refresh for ${naddr}`, { url: refreshUrl, hasSecret: !!secret })
-    
-    fetch(refreshUrl, {
-      method: 'POST',
-      headers: { 'x-refresh-key': secret },
-      keepalive: true
-    })
-      .then(async (resp) => {
-        try {
-          const result = await resp.json()
-          console.log(`Background refresh response for ${naddr}:`, { status: resp.status, result })
-        } catch (e) {
-          console.log(`Background refresh response for ${naddr}:`, { status: resp.status, text: await resp.text().catch(() => 'failed to read') })
-        }
-      })
-      .catch((err) => {
-        console.error(`Background refresh fetch failed for ${naddr}:`, err instanceof Error ? err.message : err)
-      })
-  }
-
   // Generate and send HTML
   const html = generateHtml(naddr, meta)
   setCacheHeaders(res, cacheMaxAge)