[BUG] 多账号受限后无法自动切换，上下文达到一定长度后会出现timeout

1. 添加多账号后，当一个账号“exceed your account's rate limit”，无法启动切换到另一个没受限的账号，需要手动删除受限的账号。
2. 上下文达到一定长度后会出现反复timeout，并retry，新开一个对话就好了：

    … +273 lines (ctrl+r to expand)
  ⎿  API Error (Request timed out.) · Retrying in 1 seconds… (attempt 1/10)
  ⎿  API Error (Request timed out.) · Retrying in 1 seconds… (attempt 2/10)
  ⎿  API Error (Request timed out.) · Retrying in 2 seconds… (attempt 3/10)
  ⎿  API Error (Request timed out.) · Retrying in 5 seconds… (attempt 4/10)
  ⎿  API Error (Request timed out.) · Retrying in 8 seconds… (attempt 5/10)
  ⎿  API Error (Request timed out.) · Retrying in 16 seconds… (attempt 6/10)
  ⎿  API Error (Request timed out.) · Retrying in 33 seconds… (attempt 7/10)
  ⎿  API Error (Request timed out.) · Retrying in 34 seconds… (attempt 8/10)
  ⎿  API Error (Request timed out.) · Retrying in 33 seconds… (attempt 9/10)
  ⎿  API Error (Request timed out.) · Retrying in 37 seconds… (attempt 10/10)
  ⎿  API Error: Request timed out.