fix: audio regions on silent video, interleaved >2ch stride, coderabbit config

- Fall back to video container duration when mainBuffer is null but
  audioRegions are present (prevents empty output)
- Use data.numberOfChannels as deinterleave stride instead of capped
  dataChannels (fixes garbled audio for 5.1+ sources)
- Fix .coderabbit.yaml: '*' is not valid regex, use '.*'

.coderabbit.yaml

@@ -2,4 +2,4 @@ reviews:
   auto_review:
     enabled: true
     base_branches:
-      - "*"
+      - ".*"

src/lib/exporter/audioEncoder.ts

@@ -593,7 +593,7 @@ export class AudioProcessor {
 		let sourceDurationSec: number;
 		if (mainBuffer) {
 			sourceDurationSec = mainBuffer.duration;
-		} else if (hasExternalSources) {
+		} else if (hasExternalSources || regionEntries.length > 0) {
 			sourceDurationSec = await this.getMediaDurationSec(videoUrl);
 		} else {
 			sourceDurationSec = primaryBuffer?.duration ?? 0;
@@ -983,20 +983,23 @@ export class AudioProcessor {
 								);
 							}
 						} else if (format) {
-							// Interleaved format — deinterleave into per-channel arrays
+							// Interleaved format — deinterleave into per-channel arrays.
+							// Use data.numberOfChannels as stride (not capped dataChannels)
+							// since the raw buffer contains all source channels.
+							const srcChannels = data.numberOfChannels;
 							const size = data.allocationSize({ planeIndex: 0 });
 							const bytes = new ArrayBuffer(size);
 							data.copyTo(bytes, { planeIndex: 0 });
 							const interleaved = this.rawToFloat32(
 								bytes,
 								format,
-								frames * dataChannels,
+								frames * srcChannels,
 							);
 							for (let ch = 0; ch < dataChannels; ch++) {
 								const chData = new Float32Array(frames);
 								for (let i = 0; i < frames; i++) {
 									chData[i] =
-										interleaved[i * dataChannels + ch];
+										interleaved[i * srcChannels + ch];
 								}
 								channelChunks[ch].push(chData);
 							}