Refactor: split monolithic main.py into core/, widgets/, ui/ packages

[Copilot]

main.py was a 1598-line monolith mixing executor logic, terminal widget, dynamic param UI, script discovery, and the main window. This refactor splits responsibilities into focused modules while preserving 100% backward compatibility with all existing task scripts.

New structure

Module	Responsibility
core/i18n.py	Shared UI_TEXTS singleton; load_ui_texts() mutates it in-place so all modules share one dict
core/utils.py	resource_path() — PyInstaller-compatible path resolver
core/executor.py	ScriptExecutor(QThread) — QProcess, output decoding, [PROGRESS] parsing, send_input/terminate
core/script_registry.py	scan(), parse_params(), extract_docstring()
widgets/terminal.py	EnhancedTerminalWidget
widgets/dynamic_params.py	DynamicParamsWidget — build_ui(params, lang) / build_args() / clear()
ui/main_window.py	ScriptGUI(QMainWindow)
main.py	62-line launcher

Parameter parsing — backward-compatible --gui-schema extension

parse_params() tries --gui-schema first (returns structured JSON); falls back to the original --help regex heuristic for legacy scripts:

# New scripts can emit JSON schema:
# python script.py --gui-schema  →  [{"name": "--sort", "type": "choice", ...}]
#
# Old scripts unchanged — --help regex fallback fires automatically
params = registry.parse_params(script_path)   # transparent to caller

Bugs fixed

• self.progress_label = None assigned twice in __init__ — duplicate removed
• self.run_button.setText(lang['run_button']) called twice in _update_ui_language — duplicate removed
• _refresh_scripts: was enabling the Stop button (wrong) and _clear_dynamic_params_ui() was unreachable inside a comment — both corrected
• _on_script_finished: statusBar().showMessage(...) was inside an inline comment and never executed — fixed
• Dead monkey-patch in _dynamic_params_resize_event (line 646 in original was unreachable) — replaced by DynamicParamsWidget.resizeEvent override
• _get_union_of_marked_items() extracted as a helper, eliminating duplicated selected+checked union logic in _on_remove_button_clicked and keyPressEvent

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