Add ACP agent backend and terminal controls

app/src/ai/acp/mod.rs

@@ -0,0 +1,23 @@
+//! Agent Client Protocol integration for Galaxy's native agent conversation UI.
+//!
+//! ACP is a conversation backend, not an LLM provider. The external agent owns
+//! its model, authentication, prompt loop, and tool execution. Galaxy owns the
+//! process lifecycle, permissions, visible transcript, and local tool bridge.
+
+mod launch;
+mod permissions;
+mod prompt;
+mod response_translator;
+mod runtime_model;
+mod transport;
+
+pub(crate) use launch::{
+    acp_launch_fingerprint, acp_model_id, resolve_acp_launch, validate_acp_dispatch,
+    validate_acp_launch_identity,
+};
+pub(crate) use permissions::resolve_acp_permissions;
+pub(crate) use runtime_model::AcpRuntimeModel;
+pub(crate) use transport::{
+    acp_output_stream, acp_startup_error_stream, galaxy_mcp_server, AcpSessionHandleSlot,
+    AcpSessionMetadata, AcpSteeringRequest, GalaxyMcpTarget,
+};