Task 18: Add command palette (Ctrl+K)

- Create CommandPalette.tsx with overlay, search input, grouped results,
  keyboard navigation (arrows, Enter, Escape), and footer hints
- Rebuild search.ts with PaletteItem model: 24 entries across 6 sections
  (Experience, Core Skills, Active Projects, Achievements, Education,
  Quick Actions) matching concept HTML structure
- Fuzzy search via fuse.js with weighted keys (title, subtitle, keywords)
- Wire into DashboardLayout with global Ctrl+K listener and TopBar click
- Action system: scroll-to-tile, expand-item, external links, download CV
- Add data-tile-id to all Card/tile components for scroll targeting
- CSS animations: palette-overlay-in, palette-modal-in with
  prefers-reduced-motion support
- Maintain backward-compatible legacy exports for ClinicalSidebar
  (will be removed in Task 21)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/tiles/CoreSkillsTile.tsx

@@ -233,7 +233,7 @@ export function CoreSkillsTile() {
   )
 
   return (
-    <Card>
+    <Card tileId="core-skills">
       <CardHeader dotColor="amber" title="REPEAT MEDICATIONS" />
       <div style={{ display: 'flex', flexDirection: 'column', gap: '10px' }}>
         {skills.map((skill) => (