v1.1.50-open-runtime-fork.3

fix(plugin): remove unnecessary default auth plugins from BUILTIN

These third-party auth plugins (opencode-anthropic-auth, gitlab-auth) are
unnecessary for our embedded runtime use case where auth is handled by the
host Dart process. They cause intermittent ERR_MODULE_NOT_FOUND failures
when Bun's compiled binary can't resolve npm packages installed at runtime
from /$bunfs/, and add ~1.5s of startup latency per execution.

Co-authored-by: Cursor <cursoragent@cursor.com>