fix proverbs state

[lawwu]

When sending a chat that updates the proverbs state, there is an error in the frontend:

 Error: Failed to execute action addProverb: TypeError: state.proverbs is not iterable
      at createConsoleError (http://localhost:3000/_next/static/chunks/c412d_next_dist_client_b5ec818c._.js:882:71)
      at handleConsoleError (http://localhost:3000/_next/static/chunks/c412d_next_dist_client_b5ec818c._.js:1058:54)
      at console.error (http://localhost:3000/_next/static/chunks/c412d_next_dist_client_b5ec818c._.js:1223:57)
      at useChat.useAsyncCallback[runChatCompletion].executeActionFromMessage
  (http://localhost:3000/_next/static/chunks/b0ba2_%40copilotkit_react-core_dist_a0202b27._.js:3115:61)
      at http://localhost:3000/_next/static/chunks/b0ba2_%40copilotkit_react-core_dist_a0202b27._.js:3452:13
      at Generator.throw (<anonymous>)
      at rejected (http://localhost:3000/_next/static/chunks/b0ba2_%40copilotkit_react-core_dist_a0202b27._.js:106:37)

This fixes the issue.

[tylerslaton]

Thanks @lawwu!

[lawwu]

@tylerslaton good to merge?