feat: add task sets functionality with CRUD operations and UI integration

- Implemented NewTaskSetPage for creating task sets with templates.
- Created TaskSetsPage for listing and filtering task sets.
- Enhanced TaskTemplatesPage with navigation to task sets.
- Updated ProjectTaskForm to support task set selection.
- Modified PageHeader to support multiple action buttons.
- Initialized database with task_sets and task_set_templates tables.
- Added queries for task sets including creation, retrieval, and deletion.
- Implemented applyTaskSetToProject function for bulk task creation.
- Added test script for verifying task sets functionality.

test-task-sets.mjs

@@ -0,0 +1,71 @@
+#!/usr/bin/env node
+
+// Test script to verify task sets functionality
+import { getAllTaskSets, createTaskSet } from './src/lib/queries/tasks.js';
+import initializeDatabase from './src/lib/init-db.js';
+
+async function testTaskSets() {
+  console.log('Testing Task Sets Database Functions...\n');
+
+  try {
+    // Initialize database
+    initializeDatabase();
+
+    // Test 1: Get all task sets
+    console.log('1. Getting all task sets...');
+    const taskSets = getAllTaskSets();
+    console.log(`Found ${taskSets.length} task sets:`);
+    taskSets.forEach(set => {
+      console.log(`  - ${set.name} (${set.task_category}):`, JSON.stringify(set));
+    });
+
+    // Test 2: Create a new task set (design)
+    console.log('\n2. Creating design task set...');
+    const designSetId = createTaskSet({
+      name: 'Test Design Set',
+      description: 'Test task set for design tasks',
+      task_category: 'design',
+      templates: []
+    });
+    console.log(`Created task set with ID: ${designSetId}`);
+
+    // Test 3: Create a construction task set
+    console.log('\n3. Creating construction task set...');
+    const constructionSetId = createTaskSet({
+      name: 'Test Construction Set',
+      description: 'Test task set for construction tasks',
+      task_category: 'construction',
+      templates: []
+    });
+    console.log(`Created task set with ID: ${constructionSetId}`);
+
+    // Test 4: Try to create invalid task set (should fail)
+    console.log('\n4. Testing invalid task category (should fail)...');
+    try {
+      const invalidSetId = createTaskSet({
+        name: 'Invalid Set',
+        description: 'This should fail',
+        task_category: 'design+construction',
+        templates: []
+      });
+      console.log('✗ Should have failed to create invalid task set');
+    } catch (error) {
+      console.log('✓ Correctly rejected invalid task category:', error.message);
+    }
+
+    // Test 5: Get all task sets again
+    console.log('\n5. Getting all task sets after creation...');
+    const updatedTaskSets = getAllTaskSets();
+    console.log(`Found ${updatedTaskSets.length} task sets:`);
+    updatedTaskSets.forEach(set => {
+      console.log(`  - ${set.name} (${set.task_category})`);
+    });
+
+    console.log('\n✅ All tests passed! Task sets functionality is working correctly.');
+
+  } catch (error) {
+    console.error('Test failed:', error.message);
+  }
+}
+
+testTaskSets();