docs: add Dialog SDK reference with WidgetData and event handlers

[pabloinigoblasco]

Summary

Quick reference for all PJ::WidgetData setters and PJ::DialogPluginTyped event handlers, organized by Qt widget type.

Contents

• WidgetData setters by widget type (QLineEdit, QComboBox, QTableWidget, etc.)
• Event handlers table with payloads
• Lifecycle hooks reference (onTick, saveConfig, etc.)
• Parser dialog injection documentation
• New features: setShortcut(), setFolderPicker(), setDisabledRows()

Test plan

• Verify markdown renders correctly
• Verify relative link to dialog-plugin-guide.md works