feat(04-03): remove t.Skip from TestTaskOrderPersists — all 9 TestTask* tests active

- Remove t.Skip("handlers_tasks not yet implemented") from TestTaskOrderPersists
- Full test suite green: go test ./... exits 0, no FAIL lines
- All 9 TestTask* tests active (skip on missing TEST_DATABASE_URL per existing pattern)

backend/internal/web/handlers_tasks_test.go

@@ -525,7 +525,6 @@ func TestTaskDelete(t *testing.T) {
 // TestTaskOrderPersists verifies that after a reorder, a subsequent GET
 // /tablos/{id} renders tasks in the new position order (TASK-07).
 func TestTaskOrderPersists(t *testing.T) {
-	t.Skip("handlers_tasks not yet implemented")
 
 	pool, cleanup := setupTestDB(t)
 	defer cleanup()