Record native Linux CPU media helper validation

docs/evidence/linux-media-runtime.json

@@ -0,0 +1,23 @@
+{
+  "platform": "Ubuntu 24.04 x86_64 under WSL",
+  "cpu_only": true,
+  "provider": "BtbN/FFmpeg-Builds",
+  "release": "autobuild-2026-10-12-13-12",
+  "archive_sha256": "12445b38a4700ba1ae7c9c7e57062f602c927dc4187555bfadc9f3e2f75f05b0",
+  "tools": {
+    "ffmpeg": {
+      "sha256": "8596cfc936ce24a1366f0a9da6aad60a9fc522aa1a9f1debe4d5abec7d0bf84c",
+      "version": "ffmpeg version n9.0.2-27-g7e93014c5b-20261012 Copyright (c) 2000-2026 the FFmpeg developers"
+    },
+    "ffprobe": {
+      "sha256": "0c14dda3e944613d2c60230ec82c7e98880a394086b82ce5cda7e12e3a6c3019",
+      "version": "ffprobe version n9.0.2-27-g7e93014c5b-20261012 Copyright (c) 2007-2026 the FFmpeg developers"
+    }
+  },
+  "fixture": "digup-speech.wav",
+  "fixture_sha256": "bfbc029af6c0bacdbaccfa6c695d6772373453249386fa6a62a7b02a31d33e1f",
+  "audio_duration_seconds": "4.000000",
+  "audio_decode_to_null": "passed",
+  "limits": "one CPU thread; hardware acceleration disabled",
+  "scope": "native decoder startup, WAV probe and decode; no playback, video codec matrix, neural relevance or GPU validation"
+}