analog_input_gain (#21)

- add input boost slider
- add level meter

Reviewed-on: https://gitea.pstruebi.xyz/auracaster/bumble-auracast/pulls/21

src/auracast/multicast_control.py

@@ -37,6 +37,12 @@ class Multicaster:
             'is_initialized': self.is_auracast_init,
             'is_streaming': streaming,
         }
+
+    def get_audio_levels(self) -> list[float]:
+        """Return current RMS audio levels (0.0-1.0) for each BIG."""
+        if self.streamer is not None and self.streamer.is_streaming:
+            return self.streamer.get_audio_levels()
+        return []
     
     async def init_broadcast(self):
         self.device_acm = multicast.create_device(self.global_conf)