feat: upgrade MCP to Docker-based architecture (Beta)

Each MCP server can now run as its own Docker container on a dedicated
per-project bridge network, enabling proper isolation and lifecycle
management. SSE transport is removed (deprecated per MCP spec) with
backward-compatible serde alias. Docker socket access is auto-enabled
when stdio+Docker MCP servers are configured.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src-tauri/src/docker/mod.rs

@@ -2,8 +2,10 @@ pub mod client;
 pub mod container;
 pub mod image;
 pub mod exec;
+pub mod network;
 
 pub use client::*;
 pub use container::*;
 pub use image::*;
 pub use exec::*;
+pub use network::*;