Fix MCP form input and add reactive MCP server state

- Fix space key not working in MCP add form by handling evt.name === "space"
  - Add support for multi-character paste sequences via evt.sequence
  - Add MCPServerDisplay type to types/tui.ts for UI display
  - Add mcpServers reactive state to app store with setMcpServers,
    addMcpServer, and updateMcpServerStatus actions
  - Update session.tsx to use store's mcpServers instead of static props
  - Update execute.tsx to update store when server is added/connected
  - Remove duplicate MCPServer interfaces from app.tsx, session.tsx,
    and mcp-select.tsx in favor of shared MCPServerDisplay type

src/commands/components/execute/execute.tsx

@@ -105,7 +105,20 @@ const defaultHandleMCPAdd = async (data: MCPAddFormData): Promise<void> => {
     data.isGlobal,
   );
 
-  await connectServer(data.name);
+  // Add to store with "connecting" status
+  appStore.addMcpServer({
+    id: data.name,
+    name: data.name,
+    status: "disconnected",
+    description: data.command,
+  });
+
+  try {
+    await connectServer(data.name);
+    appStore.updateMcpServerStatus(data.name, "connected");
+  } catch {
+    appStore.updateMcpServerStatus(data.name, "error");
+  }
 };
 
 const defaultHandleBrainSetJwtToken = async (jwtToken: string): Promise<void> => {