viewer: a scheme hovered in the menu is shown live

Owner, 2026-10-19: hovering a scheme for a moment switches to it live;
moving off goes to the next one hovered or back to the one in force, to
sample schemes without re-opening the menu.

A variant's row rested on for 50 ms is worn; off every row for 50 ms,
the scheme in force again; the menu closed without a click, the one in
force at once. Only a click chooses, and a preview is never kept.
Tested with frames 10 ms apart.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

plan/served.md

@@ -247,7 +247,7 @@ The server, the CLI and the GUI find the data root with one shared function (`le
 - **Save a copy / Open with system app** on any document (`Snapshot::attachment_bytes`, snapshot.rs:328). Fixes the viewer half of defect 3.
 - **TIN click:** locally, the GUI prompts for the passphrase, reads the wrapped keyslot and the sealed record from the data root, unwraps in its own process, and returns the value to the clipboard-only path (`tests/tin_copy.rs` behaviour), then zeroizes. This is not access-logged, because the GUI never writes; the docs say so. Remotely, TINs appear only on `/h/` pages.
 - `[viewer] open_at_start` becomes a per-human eframe preference (`app.rs:833`), not journaled.
-- **Color schemes** (owner, 2026-10-19: "full blown colorscheme support … all the top neovim style colorschemes", "on the order of 20 families, each with a flyout of all its variants", a light/dark/all filter; Ayu included). The button in the sidebar's lower corner opens a menu: the filter, then, alphabetically and all on screen at once, the viewer's own family (Wanderbooks Light and Dark) and twenty families of editor schemes (Ayu, Catppuccin, Cyberdream, Dracula, Everforest, GitHub, Gruvbox, Kanagawa, Material, Melange, Monokai Pro, Night Owl, Nightfox, Nord, One Dark, Oxocarbon, Rosé Pine, Solarized, Sonokai, Tokyo Night), each a flyout of all its variants, alphabetical, each a row with a strip of its colors that chooses it. The choice and the filter are per-human eframe preferences like `open_at_start`; nothing is journaled and no figure changes (`schemes.rs` paints nine pages in all 80 schemes and checks every painted word and figure is the same, in the same place, and readable on what is under it). Every palette keeps every text color (figures, gains and losses, warnings, links, the faintest text) at WCAG AA contrast (4.5:1) on every background it is drawn on: a scheme's own color that falls short keeps its hue and only changes lightness, and gains, losses and text stay plainly different to the eye. The scheme pins egui's light or dark theme, so the system flipping changes nothing. The palettes come from each scheme's official source (`docs/color-schemes.md`).
+- **Color schemes** (owner, 2026-10-19: "full blown colorscheme support … all the top neovim style colorschemes", "on the order of 20 families, each with a flyout of all its variants", a light/dark/all filter; Ayu included). The button in the sidebar's lower corner opens a menu: the filter, then, alphabetically and all on screen at once, the viewer's own family (Wanderbooks Light and Dark) and twenty families of editor schemes (Ayu, Catppuccin, Cyberdream, Dracula, Everforest, GitHub, Gruvbox, Kanagawa, Material, Melange, Monokai Pro, Night Owl, Nightfox, Nord, One Dark, Oxocarbon, Rosé Pine, Solarized, Sonokai, Tokyo Night), each a flyout of all its variants, alphabetical, each a row with a strip of its colors that chooses it; a row rested on for 50 ms is worn live until the pointer moves on (owner, 2026-10-19), and only a click keeps it. The choice and the filter are per-human eframe preferences like `open_at_start`; nothing is journaled and no figure changes (`schemes.rs` paints nine pages in all 80 schemes and checks every painted word and figure is the same, in the same place, and readable on what is under it). Every palette keeps every text color (figures, gains and losses, warnings, links, the faintest text) at WCAG AA contrast (4.5:1) on every background it is drawn on: a scheme's own color that falls short keeps its hue and only changes lightness, and gains, losses and text stay plainly different to the eye. The scheme pins egui's light or dark theme, so the system flipping changes nothing. The palettes come from each scheme's official source (`docs/color-schemes.md`).
 
 ### 3.7 Backup and tamper evidence