Remove MCP backend, entrypoint injection, and docs; add migration shim

Completes the removal begun in the previous commit.

Backend: deletes models/mcp_server.rs, storage/mcp_store.rs and
commands/mcp_commands.rs, the McpStore on AppState, the four IPC
handlers, Project::enabled_mcp_servers, build_mcp_servers_json(),
compute_mcp_fingerprint(), the MCP_SERVERS_JSON env injection, the
mcp-fingerprint label, and the whole MCP container lifecycle.
create_container() and container_needs_recreation() lose their
mcp_servers/network_name parameters.

Container: entrypoint.sh no longer merges MCP_SERVERS_JSON into
~/.claude.json. MCP_SERVERS_JSON stays in the reserved env blocklist.

Security: the Docker socket is no longer auto-mounted for stdio+Docker
MCP servers — it now mounts only when allow_docker_access is set.

Migration: old containers were created with
network_mode=triple-c-net-<projectId> and refuse to start once that
network is gone. docker/network.rs becomes docker/legacy_cleanup.rs with
label-driven, best-effort removal of leftover MCP containers and the
per-project network, called on both delete and recreate.
container_needs_recreation() now forces a rebuild for any container
carrying a non-empty triple-c.mcp-fingerprint label or attached to a
triple-c-net-* network, moving it onto the default bridge. Both can be
dropped a release later.

Docs: drops the MCP sections from README/HOW-TO-USE/TECHNICAL and adds a
short note pointing at Claude Code's native `claude mcp` / `/mcp` /
.mcp.json instead.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src-tauri/src/lib.rs

@@ -11,14 +11,12 @@ use std::sync::Arc;
 use docker::exec::ExecSessionManager;
 use storage::projects_store::ProjectsStore;
 use storage::settings_store::SettingsStore;
-use storage::mcp_store::McpStore;
 use tauri::Manager;
 use web_terminal::WebTerminalServer;
 
 pub struct AppState {
     pub projects_store: Arc<ProjectsStore>,
     pub settings_store: Arc<SettingsStore>,
-    pub mcp_store: Arc<McpStore>,
     pub exec_manager: Arc<ExecSessionManager>,
     pub web_terminal_server: Arc<tokio::sync::Mutex<Option<WebTerminalServer>>>,
 }
@@ -40,13 +38,6 @@ pub fn run() {
             panic!("Failed to initialize settings store: {}", e);
         }
     });
-    let mcp_store = Arc::new(match McpStore::new() {
-        Ok(s) => s,
-        Err(e) => {
-            log::error!("Failed to initialize MCP store: {}", e);
-            panic!("Failed to initialize MCP store: {}", e);
-        }
-    });
     let exec_manager = Arc::new(ExecSessionManager::new());
 
     // Clone Arcs for the setup closure (web terminal auto-start)
@@ -61,7 +52,6 @@ pub fn run() {
         .manage(AppState {
             projects_store,
             settings_store,
-            mcp_store,
             exec_manager,
             web_terminal_server: Arc::new(tokio::sync::Mutex::new(None)),
         })
@@ -187,11 +177,6 @@ pub fn run() {
             commands::file_commands::download_container_file,
             commands::file_commands::download_container_backup,
             commands::file_commands::upload_file_to_container,
-            // MCP
-            commands::mcp_commands::list_mcp_servers,
-            commands::mcp_commands::add_mcp_server,
-            commands::mcp_commands::update_mcp_server,
-            commands::mcp_commands::remove_mcp_server,
             // AWS
             commands::aws_commands::aws_sso_refresh,
             // Updates