fix: improve action parser compatibility

[Rohithmatham12]

Summary

• support Doubao seed compact action output like click>point>point>x y by normalizing it into the existing structured action flow
• parse documented <|box_start|>...<|box_end|> coordinate strings and comma/space separated point tags
• replace pyautogui coordinate eval usage with safe coordinate parsing
• generate a drag gesture for scroll(start_box=..., end_box=...), which is the common mobile/emulator scroll form
• document supported parser formats and clarify that OpenAI-compatible deployment endpoints should include the /v1 suffix

Issues

Addresses #229.
Addresses #231.
Helps clarify #122.
Helps the deployment confusion discussed in #127.

Testing

python3 -m unittest tests.action_parser_test
python3 -m py_compile ui_tars/action_parser.py tests/action_parser_test.py
git diff --check

Note: make test could not run in my local environment because uv is not installed. Running the same parser unittest target directly passed; full unittest discovery additionally requires Pillow for tests/inference_test.py.

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