feat: implement E2E testing workflow and enhance XML syntax editor

- Added a new GitHub Actions workflow for end-to-end (E2E) testing, including setup for Node.js, Playwright, and server initialization.
- Introduced a setup script for E2E test fixtures to create necessary directories and files.
- Integrated CodeMirror for XML syntax editing in the XmlSyntaxEditor component, improving code highlighting and editing experience.
- Updated package dependencies in package.json and package-lock.json to include new libraries for XML handling and theming.
- Refactored various components for improved readability and consistency, including the sidebar and file browser dialog.
- Added tests for spec editor persistence to ensure data integrity across sessions.

apps/app/package.json

@@ -27,15 +27,19 @@
     "postinstall": "electron-builder install-app-deps",
     "start": "next start",
     "lint": "eslint",
+    "pretest": "node scripts/setup-e2e-fixtures.js",
     "test": "playwright test",
     "test:headed": "playwright test --headed",
     "dev:electron:wsl": "concurrently \"next dev -p 3007\" \"wait-on http://localhost:3007 && electron . --no-sandbox --disable-gpu\"",
     "dev:electron:wsl:gpu": "concurrently \"next dev -p 3007\" \"wait-on http://localhost:3007 && MESA_D3D12_DEFAULT_ADAPTER_NAME=NVIDIA electron . --no-sandbox --disable-gpu-sandbox\""
   },
   "dependencies": {
+    "@codemirror/lang-xml": "^6.1.0",
+    "@codemirror/theme-one-dark": "^6.1.3",
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
+    "@lezer/highlight": "^1.2.3",
     "@radix-ui/react-checkbox": "^1.3.3",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",
@@ -46,6 +50,7 @@
     "@radix-ui/react-tabs": "^1.1.13",
     "@radix-ui/react-tooltip": "^1.2.8",
     "@tanstack/react-query": "^5.90.12",
+    "@uiw/react-codemirror": "^4.25.4",
     "@xterm/addon-fit": "^0.10.0",
     "@xterm/addon-webgl": "^0.18.0",
     "@xterm/xterm": "^5.5.0",
@@ -122,7 +127,9 @@
       {
         "from": "../../.env",
         "to": ".env",
-        "filter": ["**/*"]
+        "filter": [
+          "**/*"
+        ]
       }
     ],
     "mac": {