fix(vscode): pre-select current dialect in the dialect picker

[LanceYing2004]

Screen.Recording.2026-04-17.at.17.31.35.mov

…(#2667)

Issues

Previously, clicking the dialect indicator in the status bar would always show the picker with "American" selected by default, even when the active document was already using another dialect such as British or Canadian. This made the UI inconsistent with the actual document state.

Description

This PR fixes the VS Code dialect picker so that it opens with the current document dialect highlighted, instead of always starting with US/American.

• added a helper to read the current dialect from the active document configuration
• replaced the simple quick pick call with a QuickPick instance so the current dialect can be preselected/highlighted when the menu opens

Demo

Video demo has been attached.

How Has This Been Tested?

I tested this change manually in the VS Code Extension Development Host.

I specifically verified:

• {Austrilian, British, Canadian, Indian} is highlighted when the active document dialect is {Austrilian, British, Canadian, Indian}
• Changing the dialect still works as expected
• Canceling the picker leaves the current dialect unchanged

Checklist

• I have performed a self-review of my own code
• I have added tests to cover my changes
• I have considered splitting this into smaller pull requests.

[hippietrail]

See also: #3181