feat: group multi-browser output by source

- Add browser source grouping metadata to SDK-created tabs, groups,
  list results, and aggregate count results.
- Render grouped local/remote browser tables consistently for clients,
  tabs, groups, windows, sessions, and remote status output.
- Document remote control, auth, HTTP gateway usage, and the refreshed
  project structure in the README.
- Add coverage for grouped output and BrowserCounts browser_groups.
- Bump the Python package, extension manifest, and lockfile to 0.15.6.
- Add a just publish helper for building and publishing release artifacts.

browser_cli/commands/windows.py

@@ -1,21 +1,18 @@
 import click
 from browser_cli.commands import client_from_ctx, handle_errors
-from browser_cli.commands.rendering import build_windows_tree, print_table_rows, print_tree
+from browser_cli.commands.rendering import build_windows_tree, print_browser_grouped_table_rows, print_tree
 from rich.console import Console
 
 console = Console()
 
 def _print_windows(windows: list[dict], *, show_browser: bool = False) -> None:
-  columns = []
-  if show_browser:
-    columns.append(("Browser", lambda window: window.get("browser", "")))
-  columns.extend([
+  columns = [
     ("ID", lambda window: window.get("id", "")),
     ("Alias", lambda window: window.get("alias") or ""),
     ("Tabs", lambda window: window.get("tabCount", "")),
     ("State", lambda window: window.get("state") or ""),
-  ])
-  print_table_rows(windows, columns, console=console, empty_message="[yellow]No windows found[/yellow]")
+  ]
+  print_browser_grouped_table_rows(windows, columns, console=console, empty_message="[yellow]No windows found[/yellow]")
 
 @click.group("windows")
 def windows_group():