feat: add annotation types management system

- Created annotation_types table with name, display_name, color, category, icon
- Implemented CRUD API endpoints for annotation types management
- Built annotation types management UI page at /annotation-types
- Updated Toolbox component to dynamically load and display annotation types
- Updated CandleChart component to use dynamic annotation types for markers
- Added seed functionality for default types (break_up, break_down, line)
- Cleaned up duplicate migration files

src/app/page.tsx

@@ -93,6 +93,12 @@ export default function Home() {
         <div className="p-6 border-b border-border">
           <h1 className="text-2xl font-semibold text-foreground">Candle Annotator</h1>
           <p className="text-sm text-muted-foreground mt-1">Chart annotation tool</p>
+          <a
+            href="/annotation-types"
+            className="mt-3 inline-block text-sm text-blue-600 hover:text-blue-800 underline"
+          >
+            Manage Annotation Types
+          </a>
         </div>
         <div className="p-6">
           <FileUpload onUploadSuccess={handleUploadSuccess} />