chore: import Local-Cursor v1.1.8 source snapshot

Includes the current working directory changes. Historical commits and release binaries are excluded to limit Gitea storage.
Source base: d7515973fbfd6dd2001fa156c483455b8081c7cb

internal/backend/server/errors.go

@@ -0,0 +1,5 @@
+package server
+
+import "errors"
+
+var ErrInvalidBidiAppendPayload = errors.New("invalid bidi append payload")