feat(sdk): improve Python SDK ergonomics

- Position browser-cli as a CLI plus Python SDK in docs and package metadata.
- Add public target properties and a raw command escape hatch for unsupported commands.
- Add convenience helpers for opening, finding, closing, and accessing tabs.
- Add plural group aliases and a wait_for_selector DOM convenience alias.
- Extend bound Tab objects with screenshot, pin, refresh, load wait, and URL watch helpers.
- Preserve remote auth key configuration when binding remote Tab and Group objects.
- Bump project and extension versions to 0.9.9 and cover SDK additions with tests.

extension/manifest.json

@@ -1,8 +1,8 @@
 {
   "manifest_version": 3,
   "name": "browser-cli",
-  "version": "0.9.8",
-  "description": "Control your browser from the terminal via browser-cli",
+  "version": "0.9.9",
+  "description": "Control your browser from the terminal or Python SDK",
   "permissions": [
     "tabs",
     "tabGroups",