Incoming files are now held in memory via PendingFileManager instead of
being auto-saved to disk. Users must explicitly accept files before they
are written. This prevents attackers from exhausting device storage.
Key changes:
- Add PendingFileManager with configurable limits (max 10 files, 5MB total)
- Files auto-expire after 5 minutes if not accepted
- LRU eviction when limits are exceeded
- Pending files cleared during panic mode (emergencyDisconnectAll)
- Add didReceivePendingFileTransfer delegate method
- Add acceptPendingFile/declinePendingFile to Transport protocol
Security audit reference: Cure53 BCH-01-002 (Medium severity)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
