Share native theme components and fix dialog backdrop blur

Centralize native palettes, presets, typography, controls, menus, calendar rendering, and icon assets in ferese-theme. Reuse the shared components across the shell, settings, lock screen, authentication prompt, and screen-sharing chooser.

Attach themed dialogs to compositor-owned materials, correct backdrop capture and sampling across output transforms, smooth patterned backgrounds, and prevent clipped picker buttons with the configured shell font.

crates/ferese-theme/assets/icons/status/volume-high.svg

@@ -0,0 +1,7 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 60 60" role="img" aria-label="Audio">
+<g transform="translate(3 0)">
+<path d="M27.5,12.5 L15,22.5 L5,22.5 L5,37.5 L15,37.5 L27.5,47.5 Z" fill="currentColor"/>
+<path d="M34,22 Q40,30 34,38" fill="none" stroke="currentColor" stroke-width="4" stroke-linecap="round"/>
+<path d="M40,15 Q50,30 40,45" fill="none" stroke="#3d7be6" stroke-width="4" stroke-linecap="round"/>
+</g>
+</svg>