feat: initial daily-timer implementation

frontend/public/sounds/README.md

@@ -0,0 +1,10 @@
+# Sound Files
+
+Place custom MP3 sound files here:
+
+- `warning.mp3` - Plays when speaker time is running low (30 seconds by default)
+- `timeup.mp3` - Plays when speaker time expires
+- `meeting_end.mp3` - Plays when meeting ends
+
+The application uses the Web Audio API to play sounds from the frontend.
+Default sounds are embedded, but you can override them with custom files.