feat: add discard changes functionality for worktrees

- Introduced a new POST /discard-changes endpoint to discard all uncommitted changes in a worktree, including resetting staged changes, discarding modifications to tracked files, and removing untracked files.
- Implemented a corresponding handler in the UI to confirm and execute the discard operation, enhancing user control over worktree changes.
- Added a ViewWorktreeChangesDialog component to display changes in the worktree, improving the user experience for managing worktree states.
- Updated the WorktreePanel and WorktreeActionsDropdown components to integrate the new functionality, allowing users to view and discard changes directly from the UI.

This update streamlines the management of worktree changes, providing users with essential tools for version control.

apps/ui/src/components/views/board-view/dialogs/index.ts

@@ -8,3 +8,4 @@ export { EditFeatureDialog } from './edit-feature-dialog';
 export { FollowUpDialog, type FollowUpHistoryEntry } from './follow-up-dialog';
 export { PlanApprovalDialog } from './plan-approval-dialog';
 export { MassEditDialog } from './mass-edit-dialog';
+export { ViewWorktreeChangesDialog } from './view-worktree-changes-dialog';

apps/ui/src/components/views/board-view/dialogs/view-worktree-changes-dialog.tsx

@@ -0,0 +1,68 @@
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogHeader,
+  DialogTitle,
+} from '@/components/ui/dialog';
+import { FileText } from 'lucide-react';
+import { GitDiffPanel } from '@/components/ui/git-diff-panel';
+
+interface WorktreeInfo {
+  path: string;
+  branch: string;
+  isMain: boolean;
+  hasChanges?: boolean;
+  changedFilesCount?: number;
+}
+
+interface ViewWorktreeChangesDialogProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  worktree: WorktreeInfo | null;
+  projectPath: string;
+}
+
+export function ViewWorktreeChangesDialog({
+  open,
+  onOpenChange,
+  worktree,
+  projectPath,
+}: ViewWorktreeChangesDialogProps) {
+  if (!worktree) return null;
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="w-full h-full max-w-full max-h-full sm:w-[90vw] sm:max-w-[900px] sm:max-h-[100vh] sm:h-auto sm:rounded-xl rounded-none flex flex-col">
+        <DialogHeader>
+          <DialogTitle className="flex items-center gap-2">
+            <FileText className="w-5 h-5" />
+            View Changes
+          </DialogTitle>
+          <DialogDescription>
+            Changes in the{' '}
+            <code className="font-mono bg-muted px-1 rounded">{worktree.branch}</code> worktree.
+            {worktree.changedFilesCount !== undefined && worktree.changedFilesCount > 0 && (
+              <span className="ml-1">
+                ({worktree.changedFilesCount} file
+                {worktree.changedFilesCount > 1 ? 's' : ''} changed)
+              </span>
+            )}
+          </DialogDescription>
+        </DialogHeader>
+
+        <div className="flex-1 sm:min-h-[600px] sm:max-h-[60vh]  overflow-y-auto scrollbar-visible -mx-6 -mb-6">
+          <div className="h-full px-6 pb-6">
+            <GitDiffPanel
+              projectPath={projectPath}
+              featureId={worktree.branch}
+              useWorktrees={true}
+              compact={false}
+              className="mt-4"
+            />
+          </div>
+        </div>
+      </DialogContent>
+    </Dialog>
+  );
+}