Figma plugin: theme accuracy & reliability

An accuracy and reliability pass on the Figma plugin. Imports from shadcn Create now match shadcn init exactly, radius presets reach every component, and a failed theme fetch degrades visibly instead of silently.

Fixed#

• shadcn Create imports are now byte-exact against shadcn init. The primary pair could import as the wrong ramp step with a stock white foreground (e.g. lime importing #497d00 / #fafafa instead of #9ae600 / #35530e). The plugin's built-in palettes were regenerated from shadcn's current values, and fetched themes keep shadcn's hue-matched primary-foreground instead of overwriting it with a contrast-picked white or black.
• accent, ring, sidebar-primary, and chart colors now follow shadcn's actual derivation. Accent and ring come from the base color, and the sidebar brand pair comes from the theme's chart scale.
• Radius choices now reach every component. A preset radius (e.g. None) scales all per-component radius bindings, including inputs, selects, badges, tabs, sliders, and Pro components, the same way the web's --radius-derived scale does, instead of only the semantic ladder.
• Changing Style in Create no longer resets your other selections, matching shadcncraft.com/create. Style defaults still apply on first load and Reset.
• Rhea was missing from the style defaults table, so selecting it left fields on the previous style's values.

Improved#

• Theme fetching is no longer a single point of failure. Imports route through a first-party proxy with public fallbacks, each on a short timeout. A failed fetch falls back to the plugin's built-in palettes (now exact) with a visible notice instead of degrading silently, and invalid style and color combinations surface shadcn's actual error.
• The Feedback link moved from the plugin footer into Settings.

Round-trip parity with shadcn init is now verified across every style, base color, and theme combination as part of the release process.