test: fix db test to handle sqlite system tables

tests/unit/db.test.ts

@@ -18,7 +18,10 @@ describe('Database', () => {
       .all()
       .map((t: any) => t.name);
     
-    expect(tables.sort()).toEqual(['groups', 'task_assignments', 'tasks', 'users'].sort());
+    const expectedTables = ['groups', 'task_assignments', 'tasks', 'users'];
+    // Filter out system tables like sqlite_sequence
+    const userTables = tables.filter(t => !t.startsWith('sqlite_'));
+    expect(userTables.sort()).toEqual(expectedTables.sort());
 
     // Verify tasks table schema
     const tasksColumns = db
@@ -27,5 +30,14 @@ describe('Database', () => {
       .map((c: any) => c.name);
     expect(tasksColumns).toContain('description');
     expect(tasksColumns).toContain('due_date');
+
+    // Verify foreign key constraint
+    const fkInfo = db
+      .query("PRAGMA foreign_key_list(task_assignments)")
+      .all();
+    expect(fkInfo.length).toBe(1);
+    expect(fkInfo[0].from).toBe('task_id');
+    expect(fkInfo[0].to).toBe('id');
+    expect(fkInfo[0].table).toBe('tasks');
   });
 });