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/server.go

@@ -0,0 +1,43 @@
+// Package mcp provides MCP client and server implementations.
+package mcp
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+
+	"github.com/mark3labs/mcp-go/mcp"
+	"github.com/mark3labs/mcp-go/server"
+
+	"github.com/enmanuel/agents/pkg/tools"
+)
+
+// MCPServer exposes agent tools as an MCP server.
+type MCPServer struct {
+	srv    *server.MCPServer
+	logger *slog.Logger
+}
+
+// NewMCPServer creates an MCP server exposing the given tool specs.
+func NewMCPServer(name, version string, specs []tools.ToolSpec, logger *slog.Logger) *MCPServer {
+	srv := server.NewMCPServer(name, version)
+
+	for _, spec := range specs {
+		spec := spec // capture
+		tool := mcp.NewTool(spec.Name,
+			mcp.WithDescription(spec.Description),
+		)
+		srv.AddTool(tool, func(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+			// Placeholder handler — wire real execution here
+			return mcp.NewToolResultText(fmt.Sprintf("tool %s called", spec.Name)), nil
+		})
+	}
+
+	return &MCPServer{srv: srv, logger: logger}
+}
+
+// ServeStdio runs the MCP server over stdin/stdout (for Claude Desktop / CLI integration).
+func (m *MCPServer) ServeStdio(ctx context.Context) error {
+	m.logger.Info("mcp server starting on stdio")
+	return server.ServeStdio(m.srv)
+}