fix(playback): structure MPEG-TS diagnostics (#1327)

* docs(playback): design structured mpegts diagnostics

* docs(playback): plan structured mpegts diagnostics

* fix(playback): structure mpegts error evidence

* fix(playback): structure HTML5 mpegts errors

* fix(playback): share mpegts evidence across players

* fix(playback): render structured mpegts evidence

* docs(playback): document structured mpegts diagnostics

* chore(playback): keep diagnostics lint clean

* docs(playback): complete mpegts diagnostics plan

.changes/playback-structured-mpegts-diagnostics.md

@@ -0,0 +1,9 @@
+---
+type: fix
+area: playback
+issues: [1159]
+---
+
+MPEG-TS playback errors now show exact engine evidence, including HTTP status,
+without exposing provider response details. Format, codec, truncated-stream,
+and MediaSource failures now produce more accurate fallback guidance.