feat(mcp): add display subsystem skeleton

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/mcp/subsystem.go

@@ -0,0 +1,39 @@
+// pkg/mcp/subsystem.go
+package mcp
+
+import (
+	"forge.lthn.ai/core/go/pkg/core"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+// Subsystem implements the MCP Subsystem interface via structural typing.
+// It registers GUI tools that translate MCP tool calls to IPC messages.
+type Subsystem struct {
+	core *core.Core
+}
+
+// New creates a display MCP subsystem backed by the given Core instance.
+func New(c *core.Core) *Subsystem {
+	return &Subsystem{core: c}
+}
+
+// Name returns the subsystem identifier.
+func (s *Subsystem) Name() string { return "display" }
+
+// RegisterTools registers all GUI tools with the MCP server.
+func (s *Subsystem) RegisterTools(server *mcp.Server) {
+	s.registerWebviewTools(server)
+	s.registerWindowTools(server)
+	s.registerLayoutTools(server)
+	s.registerScreenTools(server)
+	s.registerClipboardTools(server)
+	s.registerDialogTools(server)
+	s.registerNotificationTools(server)
+	s.registerTrayTools(server)
+	s.registerEnvironmentTools(server)
+	s.registerBrowserTools(server)
+	s.registerContextMenuTools(server)
+	s.registerKeybindingTools(server)
+	s.registerDockTools(server)
+	s.registerLifecycleTools(server)
+}