fix(audio): low-samplerate ogg encode + post-2.0 QA hygiene

Quality-VBR ogg (libvorbis -q:a) fixes 8 kHz 'encoder setup failed' in both ogg paths; drop empty COOKIE_SECRET ENV (app auto-generates); emit real bundle extractedSize; fix stale image-pad/compress-pdf QA specs.

apps/api/src/lib/media-tool.ts

@@ -94,7 +94,10 @@ const AUDIO_OUTPUTS: Record<string, AudioOutput> = {
   ".ogg": {
     ext: ".ogg",
     contentType: "audio/ogg",
-    encodeArgs: ["-c:a", "libvorbis", "-b:a", "192k"],
+    // Quality-based VBR, not a fixed bitrate: libvorbis fails with "encoder setup
+    // failed" when a high fixed bitrate (192k) is requested for a low sample rate
+    // (e.g. 8 kHz mono). -q:a 6 is ~192 kbps for normal audio and adapts to the rate.
+    encodeArgs: ["-c:a", "libvorbis", "-q:a", "6"],
   },
   ".opus": {
     ext: ".opus",

apps/api/src/routes/tools/convert-audio.ts

@@ -43,17 +43,13 @@ export function registerConvertAudio(app: FastifyInstance) {
             ];
           case "wav":
             return ["-i", inPath, "-vn", "-c:a", "pcm_s16le", out];
-          case "ogg":
-            return [
-              "-i",
-              inPath,
-              "-vn",
-              "-c:a",
-              "libvorbis",
-              "-b:a",
-              `${settings.bitrateKbps}k`,
-              out,
-            ];
+          case "ogg": {
+            // libvorbis ABR (-b:a) fails with "encoder setup failed" when the bitrate is
+            // too high for the source sample rate (e.g. 8 kHz). Use quality VBR (-q:a),
+            // which adapts to the rate. Map bitrate -> quality (~bitrate/32: 192k -> q6).
+            const quality = (settings.bitrateKbps / 32).toFixed(1);
+            return ["-i", inPath, "-vn", "-c:a", "libvorbis", "-q:a", quality, out];
+          }
           case "flac":
             return ["-i", inPath, "-vn", "-c:a", "flac", out];
           case "m4a":