feat(player): clip mode - mark a range of what is playing and cut it into a download

Both players get a scissors in their control row (Plex: the control row; YouTube: the actions and
the docked bar), `c`, and `[` / `]` to mark at the playhead. The clip panel lives in the player, so
the watched video is the preview: an overview of the whole item and a zoomed strip around the
selection whose ends are sliders (arrows step a tenth, Shift a second), Start / End fields with
nudges and "to the playhead", the length, a looping Play selection, a name, Cut. Escape closes the
panel before the player and the focus goes back to the scissors. A cut is a toast with a Downloads
link plus the usual Ready notification.

- ui/RangeTrack + RulerTicks: the shared, domain-free time track (regions, keyboard-steppable
  handles with a 1.5rem hit area, a playhead, a background slot, over a window of the item). The
  Downloads editor's cuts moved onto it, so they are keyboard-steppable now.
- lib/clipRange holds the marking rules (1 s to 10 min, the server's), lib/timecode the editing
  timecode the editor's private tc/parseTc became.
- keymap: a symbol typed through AltGr answers its bare-symbol row - on the HU layout `[` is
  AltGr+F, which arrives as Ctrl+Alt; letter and Mod rows still never match Ctrl+Alt.
- The YouTube stage sits in a wrapper with the panel, so the maximised stage's blur escape matches
  at any depth.
- media-scope: fields on the always-dark player chrome read white in a light theme too.

docs/DESIGN.md

@@ -545,6 +545,20 @@ of a full-width panel and nothing on the right.
   open. Stacked, the description opens from an ⓘ, because a hover popover never opens on a tap (measured
   live). The wheel: over the video it sets the volume; over a panel with something to scroll it scrolls
   only, never the volume, even at its end; over one with nothing to scroll it sets the volume. [WCAG 1.4.13]
+- **Clip mode (both players, owner's picks A + P1 + a):** a scissors in the control row (Plex: the C5 row,
+  before the ⋯; YouTube: the actions beside Download, and the docked bar) or `C` opens a clip panel IN the
+  player; `[` / `]` mark the start / end at the playhead and open it when shut. The video being watched is the
+  preview — no second stream. Plex: the panel takes the seek bar's and the row's place. YouTube: it sits under
+  the video (the card's fit counts it, so the video shrinks to make room), and a big view steps back to the
+  card. The panel: an overview of the whole item (the selection and the zoomed window on it), a zoomed strip
+  around the selection with the two ends (`ui/RangeTrack`: each end a slider — arrows step a tenth,
+  Shift a second; drawn 4px, hit 1.5rem), Start / End fields with a tenth back / forward and "to the
+  playhead", the length, Play selection (loops), a name, Cancel / Cut clip. On the always-dark chrome the
+  ends are white and the playhead amber (a light theme's accent all but vanished there). The strip's window
+  follows the selection when it settles, never under a dragging pointer. Plex seeks once a drag is
+  released (a seek may restart the transcode); YouTube follows the drag. Escape closes the panel before the
+  player; the scissors gets the focus back. A cut is a toast with a Downloads link and the usual
+  "Ready to watch" notification. Limits are the server's: 1 s to 10 min (`lib/clipRange`).
 
 ## Dialogs — _Decided_ (C4, built in S3f)
 
@@ -730,3 +744,4 @@ of a full-width panel and nothing on the right.
 | 2026-10-08 | YouTube modal chrome                             | No prev/next strips beside the card; Close an icon (the panel's top right; stacked, the title row's end); the description clamped to three lines + More; the panel shuts to a 2.75rem strip of close, expand, prev/next (option D1)                                                                                    | Keep the strips; a "Close" text button; the full description in a scroller; a panel that hides outright                                                                                                | The strips cost the video 7rem of width for a second copy of the panel's buttons; a long description pushed the channel and the actions out of sight; a hidden panel left no way to step the queue without the keyboard      |
 | 2026-10-08 | The wheel over the YouTube modal                 | Over the video: volume. Over a panel with something to scroll: scroll only, never volume, not even at its end. Over a panel with nothing to scroll: volume (owner)                                                                                                                                                     | Volume everywhere; a scroll that hands over to the volume at its end                                                                                                                                   | Reading a long description turned the volume down once it hit the end                                                                                                                                                        |
 | 2026-10-09 | A Plex show card plays                           | Its picture plays the show's next episode everywhere (an episode with a resume point → Continue + Restart, else the first unwatched, else S1·E1), resolved on the click; the preview names it once up; title and ⓘ open the show (option A + hover ask)                                                                | The picture opens the show page (as before); every card carrying `next`                                                                                                                                | A show card on Discover had no Play while Home's had one; carrying `next` costs a grid page up to 180 queries for the few cards anyone plays                                                                                 |
+| 2026-10-10 | Clip mode in the players (E38)                   | Scissors in the control row + `C`, `[` `]`; the panel in the player with the watched video as preview; overview + zoomed strip on `ui/RangeTrack` (ends are sliders); a toast + the Ready notification after Cut                                                                                                       | A ⋯ menu entry; permanent In / Out buttons; a big dialog with its own preview (a second Plex transcode / YouTube iframe)                                                                               | Owner's picks A, P1, a; a film is hours and a clip seconds, so only a zoomed strip gives a hand the precision. The Downloads editor's cuts moved onto the same track (keyboard-steppable now)                                |