fix(ui): resolve M2 blocking bugs with full POSIX fork/exec PTY spawn and tmux environment isolation

.dart_tool/package_graph.json

@@ -0,0 +1,14 @@
+{
+  "roots": [
+    "multi_agent_mux_ui_root"
+  ],
+  "packages": [
+    {
+      "name": "multi_agent_mux_ui_root",
+      "version": "1.0.0",
+      "dependencies": [],
+      "devDependencies": []
+    }
+  ],
+  "configVersion": 1
+}