Add v0.1.3 backend features: metadata fields and search

Backend Changes:
- Add estimated_minutes field to tasks (stored as integer minutes)
- Add tags field (JSON array) for categorizing tasks
- Add flag_color field for visual priority indicators
- Add search endpoint (/api/search) with project filtering
- Update JSON import to handle new metadata fields

Frontend Changes:
- Display version v0.1.3 in header
- Add search API client function
- Add format utility for time display (30m, 1.5h, etc.)

Example Data:
- Update example-import.json with time estimates, tags, and flags
- Demonstrate nested metadata inheritance

Note: Frontend UI for displaying/editing these fields in progress

frontend/src/utils/api.js

@@ -56,3 +56,12 @@ export const importJSON = (data) => fetchAPI('/import-json', {
   method: 'POST',
   body: JSON.stringify(data),
 });
+
+// Search
+export const searchTasks = (query, projectIds = null) => {
+  const params = new URLSearchParams({ query });
+  if (projectIds && projectIds.length > 0) {
+    params.append('project_ids', projectIds.join(','));
+  }
+  return fetchAPI(`/search?${params.toString()}`);
+};