Six more palettes, taking the picker to twelve

Catppuccin, Solarized, Ayu, Kanagawa, Everforest and Primer, each with the
light and dark variant its own project publishes: Latte and Mocha, Lotus
and Wave, and so on. Values were fetched from each project's own repository
and recorded in .palette-sources/palettes-upstream.md, with the two tiers
no project publishes marked derived rather than passed off as upstream.

Four candidates were rejected rather than adapted. Nord and Synthwave '84
publish no light variant, and inventing one is not porting a theme.
Monokai is proprietary and its licence forbids redistribution. Material
Theme has become a commercial product whose repository no longer publishes
a palette at all.

Body text is now lifted for contrast like every other text tone rather
than exempted and merely checked. Most of these palettes target their own
~4.5:1 for body text where ihasmail asks 7:1, so the old rule would have
rejected five of the six on a bar their designers never aimed at. Nudging
the published colour along its own hue is what the script already does for
muted text, links and accents, and every shift is printed in the generated
CSS: Solarized light moves 4.13 to 7.07, Primer needed nothing at all.

Primer is named for the design system, not for GitHub. The colour values
are MIT; the name and the logo are trademarks, and NOTICE says plainly
that nothing here is endorsed.

The picker grid already wrapped on its own, so twelve cards needed no
layout change.

web/src/views/settings/AppearanceSettings.tsx

@@ -33,6 +33,30 @@ const PALETTE_PREVIEW: Record<PaletteId, { light: string; dark: string }> = {
     light: "linear-gradient(135deg,#e6e7ed 0%,#d6d8df 55%,#2959aa 55%,#2959aa 78%,#8c4351 78%)",
     dark: "linear-gradient(135deg,#1a1b26 0%,#1f2130 55%,#7aa2f7 55%,#7aa2f7 78%,#bb9af7 78%)",
   },
+  catppuccin: {
+    light: "linear-gradient(135deg,#e6e9ef 0%,#eff1f5 55%,#8839ef 55%,#8839ef 78%,#ea76cb 78%)",
+    dark: "linear-gradient(135deg,#1e1e2e 0%,#313244 55%,#cba6f7 55%,#cba6f7 78%,#f5c2e7 78%)",
+  },
+  solarized: {
+    light: "linear-gradient(135deg,#fdf6e3 0%,#eee8d5 55%,#268bd2 55%,#268bd2 78%,#cb4b16 78%)",
+    dark: "linear-gradient(135deg,#002b36 0%,#073642 55%,#268bd2 55%,#268bd2 78%,#cb4b16 78%)",
+  },
+  ayu: {
+    light: "linear-gradient(135deg,#f8f9fa 0%,#ebeef0 55%,#f29718 55%,#f29718 78%,#55b4d4 78%)",
+    dark: "linear-gradient(135deg,#0d1017 0%,#10141c 55%,#e6b450 55%,#e6b450 78%,#39bae6 78%)",
+  },
+  kanagawa: {
+    light: "linear-gradient(135deg,#e5ddb0 0%,#f2ecbc 55%,#624c83 55%,#624c83 78%,#b35b79 78%)",
+    dark: "linear-gradient(135deg,#1f1f28 0%,#2a2a37 55%,#7e9cd8 55%,#7e9cd8 78%,#d27e99 78%)",
+  },
+  everforest: {
+    light: "linear-gradient(135deg,#efebd4 0%,#fdf6e3 55%,#8da101 55%,#8da101 78%,#df69ba 78%)",
+    dark: "linear-gradient(135deg,#2d353b 0%,#343f44 55%,#a7c080 55%,#a7c080 78%,#d699b6 78%)",
+  },
+  primer: {
+    light: "linear-gradient(135deg,#f6f8fa 0%,#ffffff 55%,#0969da 55%,#0969da 78%,#8250df 78%)",
+    dark: "linear-gradient(135deg,#0d1117 0%,#151b23 55%,#58a6ff 55%,#58a6ff 78%,#d2a8ff 78%)",
+  },
 };
 
 const MODES: Array<{ id: Mode; label: string }> = [