Support ACP as an agent

[monatis]

No description provided.

[amazon-q-developer]

This PR successfully implements Agent Client Protocol (ACP) support, adding a new communication channel for the agent. The implementation is well-structured with proper separation of concerns across protocol types, bridge utilities, and channel integration.

Key additions reviewed:

• Complete ACP protocol type definitions with JSON-RPC 2.0 support
• Session management with lifecycle handling (new, prompt, cancel, close, delete, load, resume)
• Bidirectional communication over stdio with proper async handling
• Tool kind classification and content block parsing
• Telemetry event forwarding (thoughts, tool calls, usage)
• Integration with existing bus messaging architecture

The implementation follows Rust best practices with appropriate error handling, resource management, and concurrency patterns. No blocking issues found.

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You can now have the agent implement changes and create commits directly on your pull request's source branch. Simply comment with /q followed by your request in natural language to ask the agent to make changes.

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⚠️ This PR contains more than 30 files. Amazon Q is better at reviewing smaller PRs, and may miss issues in larger changesets.