fix: bound startup-login timeout, refresh stale SKILL.md and doc comments

_startup_login() ran garminconnect's login synchronously with no timeout
before main() ever started reading stdin, so a slow/rate-limited Garmin
login could wedge a user's whole subprocess before it became responsive.
Give it the same background-thread + bounded-10s-timeout shape
_handle_authenticate already uses, with tests for both the fast-success
and timeout paths.

Also refreshes .claude/skills/geniusrun-dev/SKILL.md (still describing
the retired mcp-garmin MCP architecture) and three stale doc comments
(garmin.AuthStatus, config.GarminTokenStoreRoot, mock package doc) left
over from the direct-wrapper migration.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/internal/garmin/pyscript/tests/test_wrapper.py

@@ -124,3 +124,35 @@ def test_dispatch_unknown_cmd_is_error():
     resp = wrapper.dispatch({"id": 10, "cmd": "not_a_real_cmd"})
     assert resp["id"] == 10
     assert "unknown cmd" in resp["error"]
+
+
+def test_startup_login_success():
+    env = {"GARMIN_EMAIL": "test@example.com", "GARMIN_PASSWORD": "secret"}
+    with patch.dict("os.environ", env):
+        with patch("wrapper.Garmin") as mock_garmin_cls:
+            mock_garmin_cls.return_value = MagicMock()
+            wrapper._startup_login()
+    assert wrapper._auth_state == "authenticated"
+
+
+def test_startup_login_missing_credentials_returns_immediately():
+    with patch.dict("os.environ", {}, clear=False):
+        os.environ.pop("GARMIN_EMAIL", None)
+        os.environ.pop("GARMIN_PASSWORD", None)
+        wrapper._auth_state = "unauthenticated"
+        wrapper._startup_login()
+    assert wrapper._auth_state == "unauthenticated"
+    assert wrapper._client is None
+
+
+def test_startup_login_times_out_without_blocking():
+    env = {"GARMIN_EMAIL": "test@example.com", "GARMIN_PASSWORD": "secret"}
+    with patch.dict("os.environ", env):
+        with patch("wrapper.Garmin") as mock_garmin_cls:
+            mock_garmin_cls.return_value = MagicMock()
+            with patch.object(wrapper._login_result_queue, "get", side_effect=queue.Empty):
+                # Should return promptly (bounded by the 10s timeout passed to
+                # queue.get, which is mocked here to raise immediately) rather
+                # than blocking main()'s stdin dispatch loop from starting.
+                wrapper._startup_login()
+    assert wrapper._auth_state == "unauthenticated"