fix: address coderabbit review - clarify pre-attach guard, fix hardcoded port

Improve the comment on the pre-attach debugger guard to explain why it
only fires on the SIGUSR1 path (--inspect already has the debugger
attached by JSC at startup). Replace hardcoded port 6499 assertion in
Windows test with regex match.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/bun.js/bindings/BunDebugger.cpp

@@ -136,6 +136,10 @@ public:
         // StopTheWorld (JSC's JSON parser needs GC heap operations that conflict with STW).
         // By attaching early, we enable the pause mechanism so messages can be
         // dispatched in the normal runWhilePaused loop after STW completes.
+        // Pre-attach the debugger so that notifyNeedDebuggerBreak() can trigger a pause
+        // for CDP message dispatch. This only fires on the SIGUSR1 path because --inspect
+        // and --inspect-wait already have the debugger attached by JSC at startup
+        // (globalObject->debugger() is non-null), so the condition is false for those paths.
         auto* controllerDebugger = globalObject->inspectorController().debugger();
         if (controllerDebugger && !globalObject->debugger()) {
             controllerDebugger->attach(globalObject);

test/js/bun/runtime-inspector/runtime-inspector-windows.test.ts

@@ -93,7 +93,7 @@ describe.skipIf(!isWindows)("Runtime inspector Windows file mapping", () => {
 
     // Verify inspector actually started
     expect(targetStderr).toContain("Bun Inspector");
-    expect(targetStderr).toContain("ws://localhost:6499/");
+    expect(targetStderr).toMatch(/ws:\/\/localhost:\d+\//);
   });
 
   test("_debugProcess works with current process's own pid", async () => {