docs(release): backfill 0.23 notes for embedded MPV scaling and dock-menu fixes (#1339)

The fixes from #1206 (native view misplaced on displays scaled above 100%)
and #1207 (video jump / black bar when opening control menus) were merged
before the .changes pipeline existed and the 0.23.0 backfill missed them.
Both are user-visible and referenced from issue #1139, so they get notes.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.changes/embedded-mpv-dock-menus.md

@@ -0,0 +1,9 @@
+---
+type: fix
+area: embedded-mpv
+issues: [1139]
+---
+
+Opening the volume, audio, subtitle, speed or aspect menu in the Embedded MPV
+player no longer makes the video jump or leave a black bar above the controls:
+the menus now unfold inside the control bar instead of floating over the video.

.changes/embedded-mpv-scaled-displays.md

@@ -0,0 +1,11 @@
+---
+type: fix
+area: embedded-mpv
+issues: [1139, 1145]
+---
+
+On Windows and Linux displays scaled above 100%, the Embedded MPV video was
+drawn toward the top-left corner at a fraction of its size, in windowed and
+fullscreen mode alike. The video now fills the player area correctly at any
+display scale and page zoom, with no need for a high-DPI compatibility
+workaround.