Overhaul: 5-task implementation

- Remove TURN decks (3/4), clean up MIDI, layout
- Single cart player with 3-item autoload queue + continue toggle
- Event logging (SessionLogger), mic tracking, large mic timer widget
- LUFS metering moved from external ports to internal master mix
- Master output WAV recording with top-bar REC toggle
- Music mix output (ch 3-8 only, no mics)
- Preview bar for playlist auditioning
- Merged show log with [SONG][CART][TALK] prefixes
- Live CSV writer for OBS song display (~/live_songs.csv)
- Misc fixes: preview race condition, datetime import for recording

event_logger.py

@@ -0,0 +1,72 @@
+# event_logger.py
+
+import json
+import os
+import threading
+import time
+from datetime import datetime
+
+LOG_DIR = os.path.expanduser("~/.gti_radiostudio/sessions")
+
+
+class SessionLogger:
+    def __init__(self):
+        self._lock = threading.Lock()
+        self._log_path = None
+        self._start_new_session()
+
+    def _start_new_session(self):
+        os.makedirs(LOG_DIR, exist_ok=True)
+        ts = datetime.now().strftime("%Y-%m-%d_%H%M%S")
+        self._log_path = os.path.join(LOG_DIR, f"{ts}.jsonl")
+        self._write_raw({
+            "event": "session_start",
+            "timestamp": time.time(),
+            "iso": datetime.now().isoformat(),
+        })
+
+    def _write_raw(self, entry: dict):
+        with self._lock:
+            try:
+                with open(self._log_path, 'a') as f:
+                    f.write(json.dumps(entry) + "\n")
+            except Exception:
+                pass
+
+    def log_cart_trigger(self, track_name: str):
+        self._write_raw({
+            "event": "cart_trigger",
+            "timestamp": time.time(),
+            "iso": datetime.now().isoformat(),
+            "track": track_name,
+        })
+
+    def log_mic_on(self, channel: int):
+        self._write_raw({
+            "event": "mic_on",
+            "timestamp": time.time(),
+            "iso": datetime.now().isoformat(),
+            "channel": channel,
+        })
+
+    def log_mic_off(self, channel: int, duration_sec: float):
+        self._write_raw({
+            "event": "mic_off",
+            "timestamp": time.time(),
+            "iso": datetime.now().isoformat(),
+            "channel": channel,
+            "duration_sec": round(duration_sec, 3),
+        })
+
+    def log_deck_play(self, deck_key: str, track_name: str):
+        self._write_raw({
+            "event": "deck_play",
+            "timestamp": time.time(),
+            "iso": datetime.now().isoformat(),
+            "deck": deck_key,
+            "track": track_name,
+        })
+
+    @property
+    def log_path(self):
+        return self._log_path