feat(backlog): add branchName support to apply handler and UI components

- Updated apply handler to accept an optional branchName from the request body.
- Modified BoardView and BacklogPlanDialog components to pass currentBranch to the apply API.
- Enhanced ElectronAPI and HttpApiClient to include branchName in the apply method.

This change allows users to specify a branch when applying backlog plans, improving flexibility in feature management.

apps/ui/src/lib/electron.ts

@@ -651,7 +651,8 @@ export interface ElectronAPI {
           removedDependencies: string[];
           addedDependencies: string[];
         }>;
-      }
+      },
+      branchName?: string
     ) => Promise<{ success: boolean; appliedChanges?: string[]; error?: string }>;
     onEvent: (callback: (data: unknown) => void) => () => void;
   };