fix(debugger): extract MarteController into an importable controller package

Client/debugger was entirely package main, which Go forbids importing from
another module ("is a program, not an importable package") -- discovered
while wiring the new debugclient E2E tool against NewHeadlessMarteController.
Move martecontrol.go and its test into a new marte2debugger/controller
subpackage (package controller) and update Client/debugger/main.go to call
controller.NewMarteController/controller.DangerousCommandsEnabled. No
behavioral change to the browser-facing server.

Client/debugger/controller/cmd_gate_test.go

@@ -1,4 +1,4 @@
-package main
+package controller
 
 import (
 	"testing"

Client/debugger/controller/martecontrol.go

@@ -1,4 +1,9 @@
-package main
+// Package controller implements MarteController, the shared TCP/UDP client
+// logic that drives a running MARTe2 DebugService+TCPLogger instance. It is
+// consumed both by the Client/debugger browser-facing WebSocket server
+// (package main, via NewMarteController) and headlessly by the
+// Test/E2E/suite/debugclient E2E test tool (via NewHeadlessMarteController).
+package controller
 
 import (
 	"bufio"
@@ -21,9 +26,9 @@ import (
 // Command safety gate (CR-4)
 // ---------------------------------------------------------------------------
 
-// dangerousCommandsEnabled gates commands that mutate the RT application state
+// DangerousCommandsEnabled gates commands that mutate the RT application state
 // (FORCE, PAUSE, RESUME, STEP, BREAK, MSG).  Set via --enable-dangerous-commands.
-var dangerousCommandsEnabled = false
+var DangerousCommandsEnabled = false
 
 // dangerousCommands is the set of MARTe2 commands that can change signal values
 // or alter execution flow.  Without --enable-dangerous-commands these are blocked
@@ -319,7 +324,7 @@ func (m *MarteController) HandleBrowserCommand(msg []byte) {
 		// (DISCOVER, TREE, INFO, LS, VALUE, TRACE, UNTRACE, STEP_STATUS) are
 		// forwarded to the MARTe2 TCP control connection.
 		if isDangerousCommand(cmd) {
-			if !dangerousCommandsEnabled {
+			if !DangerousCommandsEnabled {
 				m.sink(map[string]any{
 					"type": "log", "time": time.Now().Format("15:04:05.000"),
 					"level": "WARNING",

Client/debugger/main.go

@@ -10,6 +10,8 @@ import (
 	"net/http"
 	"os"
 
+	"marte2debugger/controller"
+
 	"marte2/common/wshub"
 )
 
@@ -21,7 +23,7 @@ var staticFiles embed.FS
 func main() {
 	addr := flag.String("addr", ":7777", "HTTP listen address")
 	sourcesFile := flag.String("sources-file", "", "JSON file for persistent source list")
-	flag.BoolVar(&dangerousCommandsEnabled, "enable-dangerous-commands", false,
+	flag.BoolVar(&controller.DangerousCommandsEnabled, "enable-dangerous-commands", false,
 		"Allow FORCE/PAUSE/RESUME/STEP/BREAK/MSG commands from the browser (CR-4 safety gate)")
 	flag.Parse()
 
@@ -29,7 +31,7 @@ func main() {
 	sm := wshub.NewSourceManager(hub, *sourcesFile)
 	hub.SetSourceManager(sm)
 
-	ctrl := NewMarteController(hub)
+	ctrl := controller.NewMarteController(hub)
 
 	go hub.Run()