- file.c split layout retained; security-hardened secure-fs helpers
(open_secure_parent/to_disk_secure/rename_secure/stat_secure) now live in
file.c with file_ prefix and are shared with file_receive.c
- file_receive.c takes the security branch's bounded allocations
(receive_data_limited, data_decompress_limited, size checks) and
STATUS_ERROR signaling
- file_send.c gains the data consistency check on file->data
- client_validation.c: stricter --tls requiring --ca, log_message style
- utils.c: hardened openat/mkdirat mkdir_r from security branch
- file.c: File/FileMetadata lifecycle and local disk helpers (~110 lines)
- file_send.c: client-side send path (file_send_single_calls, file_send_sendfile)
- file_receive.c: server-side receive/save path (file_receive, receive_incremental_check,
receive_manifest, file_save_to_disk)
- file_types.h holds shared struct definitions; file.h remains an umbrella header
so existing includes are unaffected
Completes the transfer/protocol separation started in PR #212