perf(ui): migrate icons to SVG sprite system

Replace @remixicon/react with a shared Icon component that renders
via <use href> references to a single hidden SVG sprite. This reduces
DOM node count by replacing inline SVGs with lightweight references.

- Create Icon component with sprite injection (packages/ui/src/components/icon/)
- Migrate all 164 files from @remixicon/react to Icon component
- Auto-generate sprite data from remixicon bundle (scripts/generate-icon-sprite.mjs)
- Add bun run icons:generate to package.json
- Move @remixicon/react to devDependencies
- Add icon usage instructions to theme-system skill

packages/ui/src/components/mcp/McpDropdown.tsx

@@ -1,6 +1,5 @@
 import React from 'react';
 import type { McpStatus } from '@opencode-ai/sdk/v2';
-import { RiRefreshLine } from '@remixicon/react';
 
 import {
   DropdownMenu,
@@ -20,6 +19,7 @@ import { useDirectoryStore } from '@/stores/useDirectoryStore';
 import { useMcpConfigStore } from '@/stores/useMcpConfigStore';
 import { computeMcpHealth, useMcpStore } from '@/stores/useMcpStore';
 import { McpIcon } from '@/components/icons/McpIcon';
+import { Icon } from "@/components/icon/Icon";
 import { useI18n } from '@/lib/i18n';
 
 const statusTooltip = (
@@ -132,7 +132,7 @@ export const McpDropdownContent: React.FC<McpDropdownContentProps> = ({ active,
             onClick={handleRefresh}
             aria-label={t('mcpDropdown.actions.refreshAria')}
           >
-            <RiRefreshLine className={cn('h-4 w-4', isSpinning && 'animate-spin')} />
+            <Icon name="refresh" className={cn('h-4 w-4', isSpinning && 'animate-spin')} />
           </button>
         </div>
       </div>
@@ -402,7 +402,7 @@ export const McpDropdown: React.FC<McpDropdownProps> = ({ headerIconButtonClass
                   onClick={handleRefresh}
                   aria-label={t('mcpDropdown.actions.refreshAria')}
                 >
-                  <RiRefreshLine className={cn('h-4 w-4', isSpinning && 'animate-spin')} />
+                  <Icon name="refresh" className={cn('h-4 w-4', isSpinning && 'animate-spin')} />
                 </button>
                 {closeButton}
               </div>