🐛 | Fix SonarQube issues

- Extract duplicated string literals into constants (S1192)
- Replace dict() with {} literal (S7498)
- Remove duplicate test_zero_ms (S4144)
- Remove/rename unused variables (S1481)
- Replace constant assert True with comment (S5914)
- Mark stub empty methods as intentional (S1186)
- Review 2 security hotspots as safe (S5443)

tests/test_discord_rpc.py

@@ -132,7 +132,6 @@ class TestDiscordRPC:
     def test_seek_to_adjusts_start_ts(self, rpc):
         drpc, _ = rpc
         drpc.update_song({"title": "Test"}, reset_start=True)
-        original_start = drpc._start_ts
         time.sleep(0.01)
         drpc.seek_to(position_ms=30_000)  # seek to 30s
         # Now the diff between now and start_ts should be ~30s
@@ -140,7 +139,7 @@ class TestDiscordRPC:
         assert 28 <= diff <= 32  # allow some fuzz
 
     def test_stop_disconnects_and_joins(self, rpc):
-        drpc, mock_presence = rpc
+        drpc, _ = rpc
         drpc.start()
         time.sleep(0.1)
         drpc.stop()
@@ -148,18 +147,18 @@ class TestDiscordRPC:
         assert drpc._connected is False
 
     def test_send_presence_clears_when_no_song(self, rpc):
-        drpc, mock_presence = rpc
+        drpc, _mock = rpc
         drpc.start()
         time.sleep(0.1)
         drpc.clear()
         time.sleep(0.1)
-        mock_presence.clear.assert_called()
+        _mock.clear.assert_called()
 
     def test_double_start_is_idempotent(self, rpc):
         drpc, _ = rpc
         drpc.start()
         drpc.start()  # should not crash
-        assert True
+        # If we get here without exception the test passes
 
     @mock.patch("discord_rpc.Presence")
     def test_connect_failure_graceful(self, mock_presence_cls):