Add Chrome extension cookie bridge for session import

Users logged into Alta in Chrome can now send their session cookie
to the running Electron app via a local HTTP server on port 18247,
eliminating the need for re-authentication.

- main.js: HTTP cookie server with CORS, token, domain validation
- preload.js: onExtensionCookie push-pattern IPC bridge
- renderer.js: handleExtensionCookie sets session, fetches devices
- chrome-extension/: Manifest V3 extension with popup UI
- CLAUDE.md: updated architecture docs

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

chrome-extension/manifest.json

@@ -0,0 +1,25 @@
+{
+  "manifest_version": 3,
+  "name": "Alta Proxy Tool Bridge",
+  "version": "1.0.0",
+  "description": "Send Alta session cookies to the Alta Proxy Tool desktop app.",
+  "permissions": ["cookies", "activeTab"],
+  "host_permissions": [
+    "https://*.avasecurity.com/*",
+    "https://*.avigilon.com/*",
+    "http://127.0.0.1:18247/*"
+  ],
+  "action": {
+    "default_popup": "popup.html",
+    "default_icon": {
+      "16": "icon16.png",
+      "48": "icon48.png",
+      "128": "icon128.png"
+    }
+  },
+  "icons": {
+    "16": "icon16.png",
+    "48": "icon48.png",
+    "128": "icon128.png"
+  }
+}