feat(acp): implement ACP server and q acp command

Add Agent Client Protocol (ACP) server capability to Amazon Q CLI,
allowing editors like Zed and Neovim to use Q as an AI coding assistant
through a standardized JSON-RPC interface.

Core implementation:
- Actor-based ACP server architecture with session management
- Complete ACP protocol support (initialize, sessions, prompts, streaming)
- `q acp --agent profile` command with feature gating (acp.enabled setting)
- Integration with existing Q CLI conversation and tool systems
- Transport over stdio with proper async handling

The ACP server reuses Q CLI's existing ConversationState, API client,
and tool systems, providing the same models and capabilities as
`q chat` but accessible from editors through the standardized protocol.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: nikomatsakis

Cargo.lock

@@ -1,6 +1,6 @@
 [workspace]
 resolver = "3"
-members = ["crates/amzn-codewhisperer-client", "crates/amzn-codewhisperer-streaming-client", "crates/amzn-consolas-client", "crates/amzn-qdeveloper-streaming-client", "crates/amzn-toolkit-telemetry-client", "crates/aws-toolkit-telemetry-definitions", "crates/chat-cli", "crates/semantic-search-client"]
+members = [ "acp-client-test","crates/amzn-codewhisperer-client", "crates/amzn-codewhisperer-streaming-client", "crates/amzn-consolas-client", "crates/amzn-qdeveloper-streaming-client", "crates/amzn-toolkit-telemetry-client", "crates/aws-toolkit-telemetry-definitions", "crates/chat-cli", "crates/chat-script", "crates/semantic-search-client"]
 default-members = ["crates/chat-cli"]
 
 [workspace.package]
@@ -12,6 +12,7 @@ version = "1.16.2"
 license = "MIT OR Apache-2.0"
 
 [workspace.dependencies]
+agent-client-protocol = "0.3.0"
 amzn-codewhisperer-client = { path = "crates/amzn-codewhisperer-client" }
 amzn-codewhisperer-streaming-client = { path = "crates/amzn-codewhisperer-streaming-client" }
 amzn-consolas-client = { path = "crates/amzn-consolas-client" }

Cargo.toml

@@ -16,6 +16,7 @@ default = []
 wayland = ["arboard/wayland-data-control"]
 
 [dependencies]
+agent-client-protocol.workspace = true
 amzn-codewhisperer-client.workspace = true
 amzn-codewhisperer-streaming-client.workspace = true
 amzn-consolas-client.workspace = true
@@ -39,6 +40,7 @@ bstr.workspace = true
 bytes.workspace = true
 camino.workspace = true
 cfg-if.workspace = true
+chat-script = { path = "../chat-script" }
 chrono.workspace = true
 clap.workspace = true
 clap_complete.workspace = true