refactor: upgrade go-te to v0.1.0, remove C1 normalization

go-te v0.1.0 fixes the ByteStream C1 bug (Latin-1 fallback for
invalid UTF-8 bytes), so NormalizeC1Controls is no longer needed.

Removed:
- NormalizeC1Controls function and its tests/fuzz target
- utf8Buffer field from TerminalSession and DockerExecSession
- C1BUG.md (fix shipped upstream)

The handleOutput pipeline now does: FilterDA → replay → tracker → connector
(was: FilterDA → NormalizeC1 → replay → tracker → connector)

All tests pass with -race. 13 fuzz targets remain.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

go/go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/creack/pty v1.1.18
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/gorilla/websocket v1.5.3
-	github.com/rcarmo/go-te v0.0.0-20260214100434-edf070e453db
+	github.com/rcarmo/go-te v0.1.0
 	gopkg.in/yaml.v3 v3.0.1
 )