feat(a2a): Introduce /init command for a2a server

[cocosheng-g]

This pull request introduces a new /init command and refactors the existing one to analyze a project and generate a GEMINI.md file. Here is a summary of the changes:

Core Logic (packages/core):

A new performInit function is added to check for an existing GEMINI.md file. If the file doesn't exist, it returns a prompt for generating one; otherwise, it returns an informational message.

CLI (packages/cli):

• The /init command is updated to use the new performInit function.
• If a GEMINI.md file doesn't exist, the command will create an empty one and then uses a prompt to have the agent populate it.

A2A Server (packages/a2a-server):

• A new /init command is added, which also uses the performInit function.
• The command is registered in the CommandRegistry.
• The CoderAgentExecutor is used to handle the generation of the GEMINI.md file.
• The server now supports streaming command execution via executeStream.

[gemini-cli]

Thanks for your hard work on this pull request!
This pull request is quite large, which can make it challenging and time-consuming for reviewers to go through thoroughly.
To help us review it more efficiently and get your changes merged faster, we kindly request you consider breaking this into smaller, more focused pull requests. Each smaller PR should ideally address a single logical change or a small set of related changes.
For example, you could separate out refactoring, new feature additions, and bug fixes into individual PRs. This makes it easier to understand, review, and test each component independently.
We appreciate your understanding and cooperation. Feel free to reach out if you need any assistance with this!

[gemini-cli]

Thanks for your hard work on this pull request!

This pull request is quite large, which can make it challenging and time-consuming for reviewers to go through thoroughly.

To help us review it more efficiently and get your changes merged faster, we kindly request you consider breaking this into smaller, more focused pull requests. Each smaller PR should ideally address a single logical change or a small set of related changes.

For example, you could separate out refactoring, new feature additions, and bug fixes into individual PRs. This makes it easier to understand, review, and test each component independently.

We appreciate your understanding and cooperation. Feel free to reach out if you need any assistance with this!

[gemini-cli]

👍

[gemini-cli]

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Task finished.

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I have completed the analysis of this PR. All labels are correct, and no further action is needed.

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My analysis is complete. No changes to labels were necessary.

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Task finished.

[skeshive]

Stamped 🚀