feat: enhance list-branches endpoint to support fetching remote branches

- Updated the list-branches endpoint to accept an optional parameter for including remote branches.
- Implemented logic to fetch and deduplicate remote branches alongside local branches.
- Modified the CreatePRDialog component to utilize the updated API for branch selection, allowing users to select from both local and remote branches.

apps/ui/src/lib/http-api-client.ts

@@ -1746,8 +1746,8 @@ export class HttpApiClient implements ElectronAPI {
     pull: (worktreePath: string) => this.post('/api/worktree/pull', { worktreePath }),
     checkoutBranch: (worktreePath: string, branchName: string) =>
       this.post('/api/worktree/checkout-branch', { worktreePath, branchName }),
-    listBranches: (worktreePath: string) =>
-      this.post('/api/worktree/list-branches', { worktreePath }),
+    listBranches: (worktreePath: string, includeRemote?: boolean) =>
+      this.post('/api/worktree/list-branches', { worktreePath, includeRemote }),
     switchBranch: (worktreePath: string, branchName: string) =>
       this.post('/api/worktree/switch-branch', { worktreePath, branchName }),
     openInEditor: (worktreePath: string, editorCommand?: string) =>