codebuddy-cn shipped without a short alias, making its model prefix the
longest of any provider (codebuddy-cn/glm-5.2). Add alias + uiAlias
"cbcn" so the prefix becomes cbcn/glm-5.2, consistent with qoder (qd),
kiro (kr), codex (cx). "cbcn" = CodeBuddy CN; reserves "cbai" for a
future codebuddy-ai (intl) provider.
Backward-compatible: full id codebuddy-cn/... still resolves (resolver
matches both id and alias).
Also regenerate tests/__baseline__/alias-baseline.json: idToAlias entry
codebuddy-cn now maps to cbcn, and cbcn joins the sorted modelKeys list.
Co-authored-by: Cursor <cursoragent@cursor.com>