Player: quick chat box, danmaku notifications, the player panel, smooth subtitle lift

- Quick chat (Enter in the full player, whatever plays): a box at the
  bottom centre in the control bar's place, compact and widening with
  the text, sharing its draft with the chat panel; Enter sends, Esc or an
  empty Enter closes, it closes by itself after 8 s without typing (the
  draft stays). Keys go to it; the Enter that opened it no longer reaches
  a focused button. Typing never shows the cursor or the controls: the
  frame wakes only on real mouse movement and holds the controls hidden
  while the box or its echo is up. Your sent line shows as an echo (or
  flies as your own danmaku line); your own chat toast is not repeated.
- Subtitle lift: always for the box, for the control bar as a setting
  (off); 4 eased-out sub-pos steps 42 ms apart instead of one per frame.
- Notifications: Toasts / Danmaku (off by default): chat and short notices
  fly over the full player, problems stay toasts; every knob of the look
  plus boldness, persisted, with a live preview strip in Settings.
- Player panel: ⚙ → Player settings docks a foldable glass panel at the
  right (tracks, subtitle size and lift, picture, volume, notifications,
  controls) in place of the card; Esc closes it.
- Danmaku preview: the mock dialogue follows the lift; the stand-in page
  has the chat box too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -122,6 +122,26 @@ by default, or Only when paused, or Off; messages always reach the chat,
 with their sound). Watching alone, nothing pops up or sounds about the
 party (there is nobody); the app's own notices still show.
 
+**Quick chat.** Enter in the big player opens a small chat box at the
+bottom centre without opening the chat panel, also while the video
+plays: type (the player's keys wait meanwhile), Enter sends, Esc or an
+empty Enter closes it, and it closes by itself after a few seconds
+without typing. It is the same draft as the chat panel's field, so a
+message started in one is there in the other. What you sent shows for a
+moment where the box was (or flies as your own line with danmaku, below);
+bottom subtitles move up out of its way and back, top signs stay. The
+mouse pointer and the controls stay hidden: typing is not moving the
+mouse.
+
+**Danmaku.** Settings → Notifications & sounds → Over the player →
+Notifications: Toasts (default) or Danmaku. With Danmaku, over the big
+player chat, joins, leaves, Up next and "starting now" fly right to left
+across the top of the picture instead of popping up (problems and errors
+still pop up, and everything does while the player is small). The look
+is yours to tune there, with a live preview: crossing time, how many at
+once, which band of the picture they use, opacity, size, boldness,
+outline, avatars, and a frame round your own lines.
+
 **While sitting out or in the background.** Sitting out, only chat,
 nudges, "starting now" (the video starts for the others) and Up next
 reach you; joins and leaves too if you turn on Settings → Notifications &
@@ -390,15 +410,21 @@ volume and sound set, and every sound with a preview, its own set and a switch);
 (the version, also at the bottom of every Settings page and in the
 Settings tab's tooltip; and the credits, e.g. that the Minimal player design is inspired by uosc).
 
-Player settings live in the player too: ⚙ → Player settings, at the
-right of its controls, and Settings → Player has the same ones (plus the
-controls' layout and the custom shader files). Player design: Standard or
-Minimal (below); progress line when hidden (on by default: a thin line at
-the bottom of the video while the controls are hidden); upscaling shader
-(see below); hardware decoding (auto, off or custom; auto is mpv's
-`auto-copy` on Windows, `auto` elsewhere; the env var
-`SYNC_RELAY_HWDEC` overrides it); in the player also the subtitle and
-audio track. Settings → Player → Controls: time display (elapsed / total
+Player settings live in the player too: ⚙ → Player settings opens a
+narrow panel at the right edge of the player that stays open while you
+watch (the controls hide and show as usual) until its × or Esc. Its
+sections fold: tracks (subtitles, audio), subtitles (size, above the
+controls), picture (upscaling shader, sharp video, hardware decoding),
+sound (volume), notifications (toasts or danmaku and the danmaku look)
+and controls (design, progress line). Settings → Player has the same
+ones (plus the controls' layout and the custom shader files). Player
+design: Standard or Minimal (below); progress line when hidden (on by
+default: a thin line at the bottom of the video while the controls are
+hidden); upscaling shader (see below); hardware decoding (auto, off or
+custom; auto is mpv's `auto-copy` on Windows, `auto` elsewhere; the env
+var `SYNC_RELAY_HWDEC` overrides it); subtitle size; subtitles above the
+controls (off by default: bottom lines move up while the control bar
+shows; the quick chat box always moves them). Settings → Player → Controls: time display (elapsed / total
 or remaining), controls size (normal or large), hide the controls after
 2, 3 or 5 s, and which optional buttons sit in the bar (chapter buttons,
 subtitles, audio, chat; hidden ones are still in ⚙). Every change
@@ -408,8 +434,9 @@ Anywhere in a server (unless you are typing): Space = ready / unready,
 Tab = chat & activity (Tab never moves between buttons). Anywhere:
 Ctrl+Shift+B = mark a problem in the session log. Keys while the
 player fills the window: Left/Right = seek 10 s, Up/Down = volume, Shift+Right = skip 1:30,
-PgUp/PgDn = previous / next chapter (as in mpv), F = fullscreen, Esc =
-close the chat, then fullscreen, then shrink the player to mini; from the
+PgUp/PgDn = previous / next chapter (as in mpv), F = fullscreen, Enter =
+quick chat, Esc = close the player panel, then
+the chat, then fullscreen, then shrink the player to mini; from the
 mini it asks to leave, Ctrl+R = reload video,
 `<` / `>` or Shift+P / Shift+N = previous / next Jellyfin episode,
 Ctrl+1..6 = Anime4K mode A, B, C, A+A, B+B, C+A, Ctrl+0 = shaders off.