feat: add critical missing data-testids for e2e test compatibility
Add data-testids across priority categories:
- Error handling: error-code, error-message, error-description
- Empty states: empty-results, empty-state-message, empty-results-message
- Validation errors: validation-error (city, calendar, flight number inputs)
- Schedule filters: time-range-slider, return-time-range-slider, direct/return checkboxes
- Sort controls: departure/time/arrival ascending/descending buttons
- Loader controls: loader-cancel-button
Updated 10 component templates with strategic testid placement to enable
487+ e2e tests across error-states, i18n, and schedule test suites.
gnezim
77c93fa061