test(codec): differential coverage vs rsync and wire-golden updates

Add tests/integration/test_codecs.py (accept/reject matrix and byte
differential against rsync 3.4.1 for every algorithm), extend the
checksum/compression unit tests with MD4/SHA1/none vectors and per-codec
round-trips, pin the new config golden (2.26.0), and update the version
strings and codec acceptance expectations.

tests/integration/test_fault_injection.py

@@ -36,7 +36,7 @@ from common import (  # noqa: E402
     verify_transfer,
 )
 
-PROTOCOL_VERSION = b"2.23.0"
+PROTOCOL_VERSION = b"2.26.0"
 STATUS_MANIFEST = 5
 STATUS_OK = 0