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.

tests/test_api.py

@@ -559,12 +559,37 @@ class TestTabs:
       mock_send.side_effect = [3, 4]
       result = b.tabs.count("github")
 
-    assert result == BrowserCounts(total=7, by_browser={"uuid-1": 3, "work": 4})
+    assert result == BrowserCounts(
+      total=7,
+      by_browser={"uuid-1": 3, "work": 4},
+      browser_groups={"uuid-1": "local", "work": "local"},
+    )
     assert mock_send.call_args_list == [
       call("tabs.count", {"pattern": "github"}, profile="default"),
       call("tabs.count", {"pattern": "github"}, profile="work"),
     ]
 
+  def test_tabs_count_multi_browser_keeps_remote_display_groups(self, b, mock_send):
+    with patch(
+      "browser_cli.active_browser_targets",
+      return_value=[
+        BrowserTarget("main", "browser-host.example:main", "", remote="browser-host.example:8765", display_group="browser-host.example"),
+        BrowserTarget("work", "browser-host.example:work", "", remote="browser-host.example:8765", display_group="browser-host.example"),
+      ],
+    ):
+      mock_send.side_effect = [1, 2]
+      result = b.tabs.count()
+
+    assert result == BrowserCounts(
+      total=3,
+      by_browser={"browser-host.example:main": 1, "browser-host.example:work": 2},
+      browser_groups={"browser-host.example:main": "browser-host.example", "browser-host.example:work": "browser-host.example"},
+    )
+    assert mock_send.call_args_list == [
+      call("tabs.count", {"pattern": None}, profile="main", remote="browser-host.example:8765", key=None),
+      call("tabs.count", {"pattern": None}, profile="work", remote="browser-host.example:8765", key=None),
+    ]
+
   def test_tabs_query(self, b, mock_send):
     mock_send.return_value = [TAB_DATA]
     result = b.tabs.query("example")
@@ -713,7 +738,11 @@ class TestGroups:
       mock_send.side_effect = [2, 5]
       result = b.groups.count()
 
-    assert result == BrowserCounts(total=7, by_browser={"uuid-1": 2, "work": 5})
+    assert result == BrowserCounts(
+      total=7,
+      by_browser={"uuid-1": 2, "work": 5},
+      browser_groups={"uuid-1": "local", "work": "local"},
+    )
 
   def test_group_query(self, b, mock_send):
     mock_send.return_value = [GROUP_DATA]
@@ -772,8 +801,8 @@ class TestWindows:
       result = b.windows.list()
 
     assert result == [
-      {"id": 1, "tabCount": 2, "state": "normal", "browser": "uuid-1"},
-      {"id": 2, "tabCount": 3, "state": "maximized", "browser": "work"},
+      {"id": 1, "tabCount": 2, "state": "normal", "browser": "uuid-1", "browserGroup": "local"},
+      {"id": 2, "tabCount": 3, "state": "maximized", "browser": "work", "browserGroup": "local"},
     ]
 
   def test_windows_open_without_url(self, b, mock_send):
@@ -907,8 +936,8 @@ class TestSession:
       result = b.session.list()
 
     assert result == [
-      {"name": "first", "tabs": 2, "savedAt": 1712707200000, "browser": "uuid-1"},
-      {"name": "second", "tabs": 5, "savedAt": 1712707300000, "browser": "work"},
+      {"name": "first", "tabs": 2, "savedAt": 1712707200000, "browser": "uuid-1", "browserGroup": "local"},
+      {"name": "second", "tabs": 5, "savedAt": 1712707300000, "browser": "work", "browserGroup": "local"},
     ]
     assert mock_send.call_args_list == [
       call("session.list", {}, profile="default"),