feat(workspace): expand rich cell inspector modal with XML/HTML formatting, hex viewer, and shortcut support

[ZhuchkaTriplesix]

Motivation & Problem

In lib/features/workspace/grid_cell_popover_inspector.dart, the modal cell inspector dialog only supports JSON formatting and minification:

• XML and HTML payloads cannot be formatted (despite XmlHtmlFormatter existing in the workspace).
• Binary and BLOB hex payloads cannot be formatted or inspected in byte chunks.
• There is no status bar showing text metrics (line count, character count, byte size).
• Pressing Ctrl+Enter / Meta+Enter does not save and close the dialog.

Proposed Solution

1. In _GridCellInspectorDialog (lib/features/workspace/grid_cell_popover_inspector.dart):
   • Integrate XmlHtmlFormatter with a "Format XML/HTML" action when the content contains XML/HTML tags.
   • Add Hex/BLOB formatting action for binary hex data.
   • Add a bottom status bar displaying line count, character count, and UTF-8 byte size.
   • Add Ctrl+Enter / Meta+Enter keyboard shortcut to commit changes and close.
2. Add widget tests for XML formatting, hex inspection, status indicators, and keyboard shortcuts in the inspector dialog.

Acceptance Criteria

• XML and HTML cell values can be pretty-formatted directly in the inspector modal.
• Hex byte chunks can be formatted for binary data.
• Line, character, and byte metrics are shown at the bottom of the editor.
• Ctrl+Enter / Meta+Enter commits the edit and closes the dialog.
• Unit and widget tests pass with 0 analyze warnings.