feat: add support for setting airplane mode with environment variables

[sailsdima]

Proposed changes

This PR adds environment variable support to the setAirplaneMode command. Previously, setAirplaneMode only accepted hardcoded literal values (enabled/disabled). With this change, users can now pass environment variables as well.
copilot:summary

What Changed:
SetAirplaneModeCommand - now accepts String value instead of AirplaneValue enum (to support ${...}) variable references. Variables are resolved at runtime via evaluateScripts().
YamlSetAirplaneMode - rewrote deserializer to pass through variable references at parse time; literal values are still validated eagerly.
Orchestra - Uses resolvedValue() instead of direct enum access.

Usage Example:

appId: com.example.app
env:
  airplaneOn: enabled
  airplaneOff: disabled
---
- setAirplaneMode: ${airplaneOn}
- setAirplaneMode: ${airplaneOff}
- setAirplaneMode: enabled # still works
- setAirplaneMode: disabled # still works

Testing

Does this need e2e tests? The demo app lives in e2e/demo_app/ — add a test screen and Maestro flow in the same PR. See e2e/demo_app/CLAUDE.md for details.

Unit tests:

• YamlCommandReaderTest (parsing with env vars + invalid value error),
• CommandDescriptionTest (description evaluation).

Integration test: added new test in IntegrationTest that runs runs setAirplaneMode with env variables through the full pipeline.

e2e test: Extended existing e2e setAirplaneMode.yaml to test env variable for airplane mode.

All existing tests pass with no regressions.

Issues fixed

#2878