feat: add performance controls for large browser ops

- Add throttled large-operation handling for tab, group, and session commands.
- Introduce performance profiles, audible-tab aware gentle mode, and job progress tracking.
- Support background session restores with status/cancel commands and lazy placeholders.
- Expose new perf and extension CLI groups plus matching Python SDK methods.
- Preserve pinned tabs during session snapshots and debounce auto-save updates.
- Bump browser-cli and extension versions to 0.10.0 and add pytest-cov to dev deps.
- Add coverage for performance controls, background jobs, lazy restores, and tab metadata.

extension/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "browser-cli",
-  "version": "0.9.9",
+  "version": "0.10.0",
   "description": "Control your browser from the terminal or Python SDK",
   "permissions": [
     "tabs",