Add audio channel selection (mono/left/right), show device LED count in target editor

Audio capture now produces per-channel FFT spectrum and RMS alongside
the existing mono mix. Each audio color strip source can select which
channel to visualize via a new "Channel" dropdown. This enables stereo
setups with separate left/right segments on the same LED strip.

Also shows the device LED count under the device selector in the target
editor for quick reference.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/storage/color_strip_source.py

@@ -78,6 +78,7 @@ class ColorStripSource:
             "audio_loopback": None,
             "sensitivity": None,
             "color_peak": None,
+            "audio_channel": None,
         }
 
     @staticmethod
@@ -165,6 +166,7 @@ class ColorStripSource:
                 visualization_mode=data.get("visualization_mode") or "spectrum",
                 audio_device_index=int(data.get("audio_device_index", -1)),
                 audio_loopback=bool(data.get("audio_loopback", True)),
+                audio_channel=data.get("audio_channel") or "mono",
                 sensitivity=float(data.get("sensitivity") or 1.0),
                 smoothing=float(data.get("smoothing") or 0.3),
                 palette=data.get("palette") or "rainbow",
@@ -366,6 +368,7 @@ class AudioColorStripSource(ColorStripSource):
     visualization_mode: str = "spectrum"    # spectrum | beat_pulse | vu_meter
     audio_device_index: int = -1            # -1 = default input device
     audio_loopback: bool = True             # True = WASAPI loopback (system audio)
+    audio_channel: str = "mono"             # mono | left | right
     sensitivity: float = 1.0                # gain multiplier (0.1–5.0)
     smoothing: float = 0.3                  # temporal smoothing (0.0–1.0)
     palette: str = "rainbow"                # named color palette
@@ -379,6 +382,7 @@ class AudioColorStripSource(ColorStripSource):
         d["visualization_mode"] = self.visualization_mode
         d["audio_device_index"] = self.audio_device_index
         d["audio_loopback"] = self.audio_loopback
+        d["audio_channel"] = self.audio_channel
         d["sensitivity"] = self.sensitivity
         d["smoothing"] = self.smoothing
         d["palette"] = self.palette

server/src/wled_controller/storage/color_strip_store.py

@@ -122,6 +122,7 @@ class ColorStripStore:
         visualization_mode: str = "spectrum",
         audio_device_index: int = -1,
         audio_loopback: bool = True,
+        audio_channel: str = "mono",
         sensitivity: float = 1.0,
         color_peak: Optional[list] = None,
     ) -> ColorStripSource:
@@ -215,6 +216,7 @@ class ColorStripStore:
                 visualization_mode=visualization_mode or "spectrum",
                 audio_device_index=audio_device_index if audio_device_index is not None else -1,
                 audio_loopback=bool(audio_loopback),
+                audio_channel=audio_channel or "mono",
                 sensitivity=float(sensitivity) if sensitivity else 1.0,
                 smoothing=float(smoothing) if smoothing else 0.3,
                 palette=palette or "rainbow",
@@ -292,6 +294,7 @@ class ColorStripStore:
         visualization_mode: Optional[str] = None,
         audio_device_index: Optional[int] = None,
         audio_loopback: Optional[bool] = None,
+        audio_channel: Optional[str] = None,
         sensitivity: Optional[float] = None,
         color_peak: Optional[list] = None,
     ) -> ColorStripSource:
@@ -381,6 +384,8 @@ class ColorStripStore:
                 source.audio_device_index = audio_device_index
             if audio_loopback is not None:
                 source.audio_loopback = bool(audio_loopback)
+            if audio_channel is not None:
+                source.audio_channel = audio_channel
             if sensitivity is not None:
                 source.sensitivity = float(sensitivity)
             if smoothing is not None: