v1.9.0: Full diagnostic sweep - 42 issues fixed

Critical fixes (7):
- Added global Express error handler (returns JSON instead of HTML)
- Removed caching from random endpoint (defeated purpose)
- Renamed share.jpg to share.png (MIME type mismatch)
- Fixed OG image dimensions (630 → 601)
- Fixed manifest.json icon sizes (192x192 → 512x512)
- Fixed implicit global event variable in console
- Added 9 missing endpoints to docs/endpoints.md

High fixes (12):
- Imported version from package.json (no hardcoded drift)
- Added dynamic endpoint count in stats
- Added input sanitization for mapper API (SSRF prevention)
- Added homepage caching (reduced 5 duplicate HTTP requests)
- Added rate limiting (100 requests/minute per IP)
- Added rel="noopener noreferrer" to all target="_blank" links
- Fixed trailing slash inconsistency in console
- Added noindex meta to 404.html
- Fixed docs/architecture.md controller filenames and dependency versions
- Fixed README.md dependency versions
- Added 12 missing endpoint tests

Medium fixes (22):
- Added escapeHtml helper for error messages
- Consistent favicon across all pages
- Added meta descriptions to privacy.html and tos.html
- Added OG/Twitter meta tags to privacy.html and tos.html
- Added aria-label to playground inputs
- Added aria-hidden to decorative SVGs
- Synced Twitter description with OG description
- Fixed robots.txt to disallow /api
- Added PWA fields to manifest.json
- Removed 5 unused imports
- Removed unused cookie-parser dependency
- Fixed inconsistent error handling in extractors
- Fixed resolvedSlug returning numeric ID
- Added /watch endpoint to streaming docs
- Improved test assertions and status code validation
- Deleted orphaned og-image.svg and logo.png

Low fixes (11):
- Removed redundant try/catch from extractPages
- Added max size eviction to cache
- Added cache key sorting in filter controller
- Added author meta tag
- Fixed favicon.svg font

Version bumped to 1.9.0

src/extractors/streamInfo.extractor.js

@@ -139,7 +139,11 @@ const extractServerList = async (episodeIds) => {
  */
 const extractMapperServers = async (malId, slug, timestamp) => {
   try {
-    const url = `https://mapper.nekostream.site/api/mal/${malId}/${slug}/${timestamp}`;
+    // Validate and sanitize input to prevent SSRF
+    if (!Number.isFinite(Number(malId))) throw new Error("Invalid malId");
+    if (!/^[a-zA-Z0-9-]+$/.test(slug)) throw new Error("Invalid slug");
+    if (!Number.isFinite(Number(timestamp))) throw new Error("Invalid timestamp");
+    const url = `https://mapper.nekostream.site/api/mal/${encodeURIComponent(malId)}/${encodeURIComponent(slug)}/${encodeURIComponent(timestamp)}`;
     const { data } = await axios.get(url, { headers });
 
     const servers = [];