v0.43.0

Added

• 29 new bundled themes + a Gradient family + a Vivid family (Sunset / Aurora / Twilight / Spectrum + 10 subtle gradients + 15 vivid flat themes). Each theme has bespoke accents tuned to its own canvas hue.
• --surface-gradient opt-in CSS token on .w cards — backwards-compatible for every existing theme.
• Theme builder gradient support: switch + 2 stop colour pickers + Tesserae-styled angle slider; live-updates the preview.
• Mobile tab shell on the Themes page: below 900px, Themes / Edit / Preview tabs.
• Tesserae-themed scrollbar globally: 12px-wide, soft track, rounded-pill thumb in --t-fg-soft.

Changed

• Colour palette layout in the theme builder: inline label | swatch rows with bigger swatches; ~10 fields fit where 4 used to.
• Theme strip is now sticky + viewport-bound with an always-visible scrollbar; no more "list runs past the palette card" overflow.
• User themes appear in the page editor's theme picker (was silently dropped).

Removed

• base16 family + all 10 base16 themes (Gruvbox, Solarized, Dracula, Catppuccin Mocha, Monokai, Tomorrow, One Dark). Dashboards using a base16 theme will fall back to Light on next load; rebuild via the theme builder if you want to keep one.