Extends the FileCopyJob to support PULL operations, enabling files to be
copied FROM remote devices TO the local device. Previously, only PUSH
operations worked (local -> remote).
Changes:
- Add PullRequest/PullResponse messages to FileTransferMessage enum
- Add TransferDirection enum to detect PUSH vs PULL operations
- Refactor RemoteTransferStrategy to detect direction automatically
- Implement execute_pull() for remote source -> local destination
- Add handle_pull_request() handler on the protocol side
- Add path validation for security (prevent directory traversal)
- Add integration test for PULL operations
The strategy automatically detects direction based on SdPath:
- Source is local + Destination is remote = PUSH (existing behavior)
- Source is remote + Destination is local = PULL (new behavior)
This enables users to drag files from remote device explorers to local
folders, which previously failed with 'Source must be local path' error.
Closes FILE-005
5c1c8dea88