Fix git.diff.stageHunk command to work with keyboard shortcuts (microsoft#254145)

The command now falls back to cursor-based hunk staging when no context
is provided, enabling keyboard users to stage hunks without manual selection.

Fixes microsoft#253895

Author: jiahaoxiang2000

extensions/git/src/commands.ts

@@ -1681,7 +1681,11 @@ export class CommandCenter {
 
 	@command('git.diff.stageHunk')
 	async diffStageHunk(changes: DiffEditorSelectionHunkToolbarContext | undefined): Promise<void> {
-		this.diffStageHunkOrSelection(changes);
+		if (changes) {
+			this.diffStageHunkOrSelection(changes);
+		} else {
+			await this.stageHunkAtCursor();
+		}
 	}
 
 	@command('git.diff.stageSelection')
@@ -1719,6 +1723,36 @@ export class CommandCenter {
 			await repository.stage(resource, result, modifiedDocument.encoding));
 	}
 
+	private async stageHunkAtCursor(): Promise<void> {
+		const textEditor = window.activeTextEditor;
+
+		if (!textEditor) {
+			return;
+		}
+
+		const workingTreeDiffInformation = getWorkingTreeDiffInformation(textEditor);
+		if (!workingTreeDiffInformation) {
+			return;
+		}
+
+		const workingTreeLineChanges = toLineChanges(workingTreeDiffInformation);
+		const modifiedDocument = textEditor.document;
+		const cursorPosition = textEditor.selection.active;
+
+		// Find the hunk that contains the cursor position
+		const hunkAtCursor = workingTreeLineChanges.find(change => {
+			const hunkRange = getModifiedRange(modifiedDocument, change);
+			return hunkRange.contains(cursorPosition);
+		});
+
+		if (!hunkAtCursor) {
+			window.showInformationMessage(l10n.t('No hunk found at cursor position.'));
+			return;
+		}
+
+		await this._stageChanges(textEditor, [hunkAtCursor]);
+	}
+
 	@command('git.stageSelectedRanges')
 	async stageSelectedChanges(): Promise<void> {
 		const textEditor = window.activeTextEditor;