ACP champagne (#35609)

cherry pick changes from #35510 onto latest main

Release Notes:

- N/A

---------

Co-authored-by: Nathan Sobo <nathan@zed.dev>
Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Lukas Wirth <lukas@zed.dev>

Cargo.lock

@@ -17,6 +17,7 @@ dependencies = [
  "indoc",
  "itertools 0.14.0",
  "language",
+ "language_model",
  "markdown",
  "parking_lot",
  "project",
@@ -150,6 +151,43 @@ dependencies = [
  "serde_json",
 ]
 
+[[package]]
+name = "agent2"
+version = "0.1.0"
+dependencies = [
+ "acp_thread",
+ "agent-client-protocol",
+ "agent_servers",
+ "anyhow",
+ "client",
+ "cloud_llm_client",
+ "collections",
+ "ctor",
+ "env_logger 0.11.8",
+ "fs",
+ "futures 0.3.31",
+ "gpui",
+ "gpui_tokio",
+ "handlebars 4.5.0",
+ "indoc",
+ "language_model",
+ "language_models",
+ "log",
+ "project",
+ "reqwest_client",
+ "rust-embed",
+ "schemars",
+ "serde",
+ "serde_json",
+ "settings",
+ "smol",
+ "ui",
+ "util",
+ "uuid",
+ "workspace-hack",
+ "worktree",
+]
+
 [[package]]
 name = "agent_servers"
 version = "0.1.0"
@@ -214,6 +252,7 @@ dependencies = [
  "acp_thread",
  "agent",
  "agent-client-protocol",
+ "agent2",
  "agent_servers",
  "agent_settings",
  "ai_onboarding",