AI chatbot improvements

### Description:

Creating a mega issue for AI chatbot improvements from https://github.com/BuidlGuidl/SpeedRunEthereum-v2/issues/new discussion and suggestions/improvements:

1. Updating the AI chatbot icon/text (check the suggestion from https://github.com/BuidlGuidl/SpeedRunEthereum-v2/pull/364#pullrequestreview-4068145487)

2. Should we add some mention in the Readme once we open it to all users?

3. H2 titles line-height looks too big, the titles look independent instead of the same sentence

Screenshot

4. Have a nice bridge from ai chatbot to local `/start` comamnd. Like suggest to move to local ide and use the `/start` with some prompt so that it skips the inital tutorial and move to code implementation.

Read the linked discussion and the review on PR 364 first, then locate the AI chatbot UI, README, H2 styling, and local `/start` command entry point. Confirm the intended changes for each of the four suggestions with maintainers; done means the icon/text, README guidance, heading spacing, and chatbot-to-`/start` path are all agreed and implemented.

Written by the indexing model from the issue text.