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/network.rs

@@ -0,0 +1,128 @@
+use bollard::network::{CreateNetworkOptions, InspectNetworkOptions};
+use std::collections::HashMap;
+
+use super::client::get_docker;
+
+/// Network name for a project's MCP containers.
+fn project_network_name(project_id: &str) -> String {
+    format!("triple-c-net-{}", project_id)
+}
+
+/// Ensure a Docker bridge network exists for the project.
+/// Returns the network name.
+pub async fn ensure_project_network(project_id: &str) -> Result<String, String> {
+    let docker = get_docker()?;
+    let network_name = project_network_name(project_id);
+
+    // Check if network already exists
+    match docker
+        .inspect_network(&network_name, None::<InspectNetworkOptions<String>>)
+        .await
+    {
+        Ok(_) => {
+            log::debug!("Network {} already exists", network_name);
+            return Ok(network_name);
+        }
+        Err(_) => {
+            // Network doesn't exist, create it
+        }
+    }
+
+    let options = CreateNetworkOptions {
+        name: network_name.clone(),
+        driver: "bridge".to_string(),
+        labels: HashMap::from([
+            ("triple-c.managed".to_string(), "true".to_string()),
+            ("triple-c.project-id".to_string(), project_id.to_string()),
+        ]),
+        ..Default::default()
+    };
+
+    docker
+        .create_network(options)
+        .await
+        .map_err(|e| format!("Failed to create network {}: {}", network_name, e))?;
+
+    log::info!("Created Docker network {}", network_name);
+    Ok(network_name)
+}
+
+/// Connect a container to the project network.
+pub async fn connect_container_to_network(
+    container_id: &str,
+    network_name: &str,
+) -> Result<(), String> {
+    let docker = get_docker()?;
+
+    let config = bollard::network::ConnectNetworkOptions {
+        container: container_id.to_string(),
+        ..Default::default()
+    };
+
+    docker
+        .connect_network(network_name, config)
+        .await
+        .map_err(|e| {
+            format!(
+                "Failed to connect container {} to network {}: {}",
+                container_id, network_name, e
+            )
+        })?;
+
+    log::debug!(
+        "Connected container {} to network {}",
+        container_id,
+        network_name
+    );
+    Ok(())
+}
+
+/// Remove the project network (best-effort). Disconnects all containers first.
+pub async fn remove_project_network(project_id: &str) -> Result<(), String> {
+    let docker = get_docker()?;
+    let network_name = project_network_name(project_id);
+
+    // Inspect to get connected containers
+    let info = match docker
+        .inspect_network(&network_name, None::<InspectNetworkOptions<String>>)
+        .await
+    {
+        Ok(info) => info,
+        Err(_) => {
+            log::debug!(
+                "Network {} not found, nothing to remove",
+                network_name
+            );
+            return Ok(());
+        }
+    };
+
+    // Disconnect all containers
+    if let Some(containers) = info.containers {
+        for (container_id, _) in containers {
+            let disconnect_opts = bollard::network::DisconnectNetworkOptions {
+                container: container_id.clone(),
+                force: true,
+            };
+            if let Err(e) = docker
+                .disconnect_network(&network_name, disconnect_opts)
+                .await
+            {
+                log::warn!(
+                    "Failed to disconnect container {} from network {}: {}",
+                    container_id,
+                    network_name,
+                    e
+                );
+            }
+        }
+    }
+
+    // Remove the network
+    match docker.remove_network(&network_name).await {
+        Ok(_) => log::info!("Removed Docker network {}", network_name),
+        Err(e) => log::warn!("Failed to remove network {}: {}", network_name, e),
+    }
+
+    Ok(())
+}