fix: correct SQL syntax and improve db test coverage

src/db.ts

@@ -25,7 +25,7 @@ export function initializeDatabase() {
     
     CREATE TABLE IF NOT EXISTS users (
       phone_number TEXT PRIMARY KEY,
-      wa_id TEXT NOT NULL, // WhatsApp's @s.whatsapp.net ID
+      wa_id TEXT NOT NULL, -- WhatsApp's @s.whatsapp.net ID
       name TEXT,
       last_seen TIMESTAMP
     );

tests/unit/db.test.ts

@@ -11,15 +11,21 @@ describe('Database', () => {
     initializeDatabase();
   });
 
-  test('should create all required tables', () => {
+  test('should create all required tables with correct schema', () => {
+    // Verify tables exist
     const tables = db
       .query("SELECT name FROM sqlite_master WHERE type='table'")
       .all()
       .map((t: any) => t.name);
     
-    expect(tables).toContain('tasks');
-    expect(tables).toContain('task_assignments');
-    expect(tables).toContain('users');
-    expect(tables).toContain('groups');
+    expect(tables.sort()).toEqual(['groups', 'task_assignments', 'tasks', 'users'].sort());
+
+    // Verify tasks table schema
+    const tasksColumns = db
+      .query("PRAGMA table_info(tasks)")
+      .all()
+      .map((c: any) => c.name);
+    expect(tasksColumns).toContain('description');
+    expect(tasksColumns).toContain('due_date');
   });
 });