fix: prevent browser target and focus surprises

- Respect the globally selected browser when renaming client aliases.
- Pass the resolved local profile into sync and async local transports so
  BROWSER_CLI_PROFILE is honored consistently.
- Stop tabs.active from explicitly focusing the OS browser window, avoiding
  virtual-desktop jumps during tab activation.
- Make window merging skip audible, unmuted windows so video playback windows
  are not selected as merge targets.
- Bump the Python package and extension manifest versions to 0.12.2.
- Add regression coverage for browser selection and focus-stealing behavior.

extension/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "browser-cli",
-  "version": "0.12.1",
+  "version": "0.12.2",
   "description": "Control your browser from the terminal or Python SDK",
   "permissions": [
     "tabs",