feat: import agents_and_robots platform as unibots (Matrix-out, unibus transport)

Reemplaza el scaffold del echobot por la plataforma completa de bots traida
desde ~/DataProyects/Github/agents_and_robots tras la operacion Matrix-out:
los bots ya no hablan por Matrix sino por el bus unibus (modelo todo-rooms +
E2E via shell/transportunibus sobre github.com/enmanuel/unibus/pkg/client).

- go.mod: replace de unibus -> ../unibus y de fn-registry -> ../../../.. (paths
  relativos reajustados a la nueva ubicacion dentro de fn_registry).
- app.md: bump a 0.2.0, descripcion + arquitectura + comandos + gotchas reales.
- modulo Go conservado como github.com/enmanuel/agents (sin reescribir imports).

agents_and_robots queda archivado como museo de la era Matrix.

shell/mcp/manager.go

@@ -0,0 +1,130 @@
+package mcp
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"strings"
+
+	"github.com/enmanuel/agents/internal/config"
+)
+
+// Manager manages multiple MCP client connections.
+type Manager struct {
+	clients map[string]*Client // server name → client
+	logger  *slog.Logger
+}
+
+// NewManager creates a new MCP manager and initializes all configured servers.
+func NewManager(ctx context.Context, servers []config.MCPServerCfg, logger *slog.Logger) (*Manager, error) {
+	if logger == nil {
+		logger = slog.Default()
+	}
+
+	m := &Manager{
+		clients: make(map[string]*Client),
+		logger:  logger,
+	}
+
+	for _, serverCfg := range servers {
+		if err := m.addServer(ctx, serverCfg); err != nil {
+			// Close any already-created clients before returning error
+			m.Close()
+			return nil, fmt.Errorf("failed to initialize MCP server %q: %w", serverCfg.Name, err)
+		}
+	}
+
+	logger.Info("MCP manager initialized", "servers", len(m.clients))
+	return m, nil
+}
+
+// addServer creates and adds a single MCP client to the manager.
+func (m *Manager) addServer(ctx context.Context, cfg config.MCPServerCfg) error {
+	if cfg.Name == "" {
+		return fmt.Errorf("MCP server must have a name")
+	}
+
+	// Auto-detect transport if not specified
+	transport := cfg.Transport
+	if transport == "" {
+		if cfg.Command != "" {
+			transport = "stdio"
+		} else if cfg.URL != "" {
+			transport = "sse"
+		} else {
+			return fmt.Errorf("MCP server %q must specify either command (stdio) or url (sse)", cfg.Name)
+		}
+	}
+
+	var client *Client
+	var err error
+
+	switch transport {
+	case "stdio":
+		if cfg.Command == "" {
+			return fmt.Errorf("MCP server %q with stdio transport must have a command", cfg.Name)
+		}
+		// Expand environment variables in command and args
+		command := os.ExpandEnv(cfg.Command)
+		args := make([]string, len(cfg.Args))
+		for i, arg := range cfg.Args {
+			args[i] = os.ExpandEnv(arg)
+		}
+		// Expand env vars in environment map
+		env := make(map[string]string, len(cfg.Env))
+		for k, v := range cfg.Env {
+			env[k] = os.ExpandEnv(v)
+		}
+		client, err = NewStdioClient(ctx, cfg.Name, command, args, env, m.logger)
+
+	case "sse":
+		if cfg.URL == "" {
+			return fmt.Errorf("MCP server %q with sse transport must have a url", cfg.Name)
+		}
+		url := os.ExpandEnv(cfg.URL)
+		headers := make(map[string]string, len(cfg.Headers))
+		for k, v := range cfg.Headers {
+			headers[k] = os.ExpandEnv(v)
+		}
+		client, err = NewSSEClient(ctx, cfg.Name, url, headers, m.logger)
+
+	default:
+		return fmt.Errorf("unknown transport %q for MCP server %q (must be stdio or sse)", transport, cfg.Name)
+	}
+
+	if err != nil {
+		return err
+	}
+
+	m.clients[cfg.Name] = client
+	m.logger.Info("MCP server connected", "name", cfg.Name, "transport", transport, "tools", len(client.Tools()))
+	return nil
+}
+
+// GetClient returns an MCP client by name, or nil if not found.
+func (m *Manager) GetClient(name string) *Client {
+	return m.clients[name]
+}
+
+// AllClients returns all MCP clients managed by this manager.
+func (m *Manager) AllClients() map[string]*Client {
+	return m.clients
+}
+
+// Close closes all MCP client connections.
+func (m *Manager) Close() error {
+	var errs []string
+	for name, client := range m.clients {
+		if err := client.Close(); err != nil {
+			errs = append(errs, fmt.Sprintf("%s: %v", name, err))
+		}
+	}
+
+	if len(errs) > 0 {
+		return fmt.Errorf("errors closing MCP clients: %s", strings.Join(errs, "; "))
+	}
+
+	m.logger.Info("MCP manager closed", "servers", len(m.clients))
+	return nil
+}