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.

browser_cli/commands/groups.py

@@ -103,9 +103,10 @@ def group_query(search):
 
 @group_group.command("close")
 @click.argument("group_id", type=int)
-def group_close(group_id):
+@click.option("--gentle-mode", type=click.Choice(["auto", "normal", "gentle", "ultra"]), default="auto", show_default=True, help="Throttle mode for large group operations.")
+def group_close(group_id, gentle_mode):
     """Close (ungroup and optionally close) a tab group."""
-    _handle("group.close", {"groupId": group_id})
+    _handle("group.close", {"groupId": group_id, "gentleMode": gentle_mode})
     console.print(f"[green]Group {group_id} closed[/green]")