v0.1.4: playback-control provenance log

LinTunes has spontaneously resumed playback for ~4s (then paused) four
times while trav was away — suspected phantom media-key events from the
Audioengine USB DAC's HID 'keyboard', but the pathway (MPRIS vs the
focused-window key filter) is unproven. Every control path now drops a
timestamped line in ~/.cache/lintunes/control-events.log: MPRIS Player
methods, the media-key eventFilter (with source input device where the
compositor exposes it), and Player.toggle_play/pause with position. New
lintunes/eventlog.py, 1MB rotation, never raises; conftest autouse
fixture keeps tests off the real log file.

lintunes/gui/main_window.py

@@ -10,6 +10,7 @@ from PyQt6.QtGui import QAction, QKeySequence
 
 from lintunes import mpris, tagging, theme
 from lintunes.art_search import AlbumArtFetcher
+from lintunes.eventlog import log_control
 from lintunes.inhibit import SleepInhibitor
 from lintunes.player import Player
 from lintunes.importers import file_importer
@@ -551,16 +552,32 @@ class MainWindow(QMainWindow):
                 return False
             key = event.key()
             if key == Qt.Key.Key_Space:
+                self._log_key(event, "space")
                 self.play_pause()
                 return True
             if key == Qt.Key.Key_Right:
+                self._log_key(event, "right")
                 self.player.next()
                 return True
             if key == Qt.Key.Key_Left:
+                self._log_key(event, "left")
                 self.player.previous()
                 return True
         return super().eventFilter(obj, event)
 
+    @staticmethod
+    def _log_key(event, name: str):
+        """Provenance for keys the filter acts on: which input device sent
+        the press (compositor permitting) — see eventlog module docstring."""
+        detail = ""
+        try:
+            device = event.device()
+            if device is not None:
+                detail = f"device={device.name()!r}"
+        except Exception:
+            pass
+        log_control("keyfilter", name, detail)
+
     def _on_playing_changed(self, playing: bool):
         if playing:
             self._inhibitor.inhibit()