Complete LinkSyncServer and LinkSyncExtension implementation

LinkSyncServer:
- Fix app.py imports, add CORS middleware, lifespan events
- Create api/routes.py router aggregator
- Create config/settings.py for centralized configuration
- Rewrite models/base.py with proper relationships and serialization
- Rewrite all API endpoints with real DB integration (auth, links, collections, sync, queries, tags)
- Add admin endpoints (user management, stats, audit log)
- Complete query parser with recursive descent and proper precedence
- Complete query executor with set operations and field filters
- Set up Alembic migrations with initial schema
- Create web interface (templates, CSS, JS)
- Add 42 passing tests (auth, links, collections, queries)
- Add deploy.ps1 and deploy.sh scripts
- Update README with deployment workflow

LinkSyncExtension:
- Create utils/api.js (REST client with retries, auth, error handling)
- Create utils/sync.js (3 sync modes + conflict detection)
- Create utils/collection.js (collection management)
- Create utils/query-engine.js (client-side query parser)
- Rewrite background.js (sync loop, bookmark events, message routing)
- Rewrite popup.js (tabs, settings modal, notifications, CRUD)
- Update popup.html (tabbed interface, query builder, modal)
- Update popup.css (full redesign)
- Create content/content.js (page metadata extraction)
- Create options.html/js (dedicated settings page)
- Generate icons (48x48, 96x96)
- Update manifest.json (host permissions, content scripts, options)
- Create AGENTS.md

LinkSyncExtension/content/content.js

@@ -0,0 +1,32 @@
+// LinkSync Content Script
+// Extracts page metadata for bookmark auto-fill
+
+(function () {
+    "use strict";
+
+    browser.runtime.onMessage.addListener((message, sender, sendResponse) => {
+        if (message.action === "getPageData") {
+            const data = {
+                url: window.location.href,
+                title: document.title,
+                description: getMetaDescription(),
+                favicon: getFavicon(),
+            };
+            sendResponse(data);
+        }
+        return true;
+    });
+
+    function getMetaDescription() {
+        const meta = document.querySelector('meta[name="description"]');
+        return meta ? meta.getAttribute("content") : "";
+    }
+
+    function getFavicon() {
+        const link = document.querySelector("link[rel='icon'], link[rel='shortcut icon']");
+        if (link) {
+            return link.getAttribute("href");
+        }
+        return new URL("/favicon.ico", window.location.origin).href;
+    }
+})();