fix(media): drop weba from the output allowlist

FFmpeg's muxer is named webm and refuses a .weba output ('Error initializing
the muxer'), so allowlisting the extension only converted a clear 'unsupported
format' rejection into a confusing encode-time failure. weba was added in this
PR because it appears in the input MIME map, but naming an input file and
naming an output muxer are different questions. extract_audio takes webm.

Author: waleedlatif1

apps/sim/lib/media/ffmpeg.test.ts

@@ -57,10 +57,18 @@ describe('runFfmpegOperation output format validation', () => {
       (e: Error) => e
     )
 
-    for (const format of ['mp4', 'mov', 'webm', 'mp3', 'wav', 'gif', 'webp', 'weba']) {
+    for (const format of ['mp4', 'mov', 'webm', 'mp3', 'wav', 'gif', 'webp']) {
       expect(error.message).toContain(format)
     }
   })
+
+  it('rejects weba, which FFmpeg has no muxer for', async () => {
+    // The extension appears in the input MIME map, but `ffmpeg out.weba` fails
+    // with "Error initializing the muxer" — webm is the muxer's real name.
+    await expect(runFfmpegOperation('convert', [mediaFile()], { format: 'weba' })).rejects.toThrow(
+      'Unsupported output format'
+    )
+  })
 })
 
 describe('runFfmpegOperation scale bounds', () => {

apps/sim/lib/media/ffmpeg.ts

@@ -189,7 +189,6 @@ const EXT_TO_MIME: Record<string, string> = {
   flac: 'audio/flac',
   aac: 'audio/aac',
   opus: 'audio/opus',
-  weba: 'audio/webm',
   png: 'image/png',
   jpg: 'image/jpeg',
   jpeg: 'image/jpeg',
@@ -216,16 +215,20 @@ const OUTPUT_EXTS = new Set([
   'flac',
   'aac',
   'opus',
-  'weba',
   'png',
   'jpg',
   'jpeg',
   'gif',
   'webp',
 ])
 
-/** extract_audio can only name an audio container; the rest would silently produce nothing useful. */
-const AUDIO_EXTS = new Set(['mp3', 'm4a', 'wav', 'ogg', 'flac', 'aac', 'opus', 'weba'])
+/**
+ * extract_audio can only name an audio container; the rest would silently
+ * produce nothing useful. `webm`, not `weba` — FFmpeg's muxer is named webm and
+ * it refuses a .weba output, so allowlisting that extension would only produce
+ * a muxer error at encode time.
+ */
+const AUDIO_EXTS = new Set(['mp3', 'm4a', 'wav', 'ogg', 'flac', 'aac', 'opus', 'webm'])
 
 /**
  * Temp-file names are built as `${prefix}.${ext}` and joined against the temp