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/format.js

@@ -0,0 +1,17 @@
+// Format minutes into display string
+export function formatTime(minutes) {
+  if (!minutes || minutes === 0) return null;
+
+  if (minutes < 60) {
+    return `${minutes}m`;
+  }
+
+  const hours = minutes / 60;
+  return `${hours.toFixed(1)}h`;
+}
+
+// Format tags as comma-separated string
+export function formatTags(tags) {
+  if (!tags || tags.length === 0) return null;
+  return tags.join(', ');
+}