Extract isomorphic @getpaseo/highlight package with syntax-highlighted file preview

- Create packages/highlight with shared Lezer-based syntax highlighting (types, parsers, highlighter, color maps)
- Add syntax highlighting and line numbers to file-pane.tsx with memoized CodeLine component
- Import shared highlight colors in git-diff-pane.tsx instead of local definitions
- Delete duplicated syntax-highlighter.ts from both app and server
- Fix TSX dialect to "ts jsx" (correct per Lezer docs)

packages/app/package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "start": "expo start",
     "reset-project": "node ./scripts/reset-project.js",
-    "build:workspace-deps": "npm run build --prefix ../expo-two-way-audio",
+    "build:workspace-deps": "npm run build --workspace=@getpaseo/highlight && npm run build --prefix ../expo-two-way-audio",
     "eas-build-post-install": "npm run build:workspace-deps",
     "android": "npm run android:development",
     "android:development": "APP_VARIANT=development expo prebuild --platform android --non-interactive && APP_VARIANT=development expo run:android --variant=debug",
@@ -22,7 +22,7 @@
     "test:e2e": "playwright test",
     "test:e2e:ui": "playwright test --ui",
     "build": "npm run build:web",
-    "build:web": "expo export --platform web",
+    "build:web": "npm run build:workspace-deps && expo export --platform web",
     "deploy:web": "npm run build:web && wrangler pages deploy dist --project-name paseo-app --branch main"
   },
   "dependencies": {
@@ -32,24 +32,10 @@
     "@expo/vector-icons": "^15.0.2",
     "@floating-ui/react-native": "^0.10.7",
     "@getpaseo/expo-two-way-audio": "0.1.32",
+    "@getpaseo/highlight": "*",
     "@getpaseo/server": "0.1.32",
     "@gorhom/bottom-sheet": "^5.2.6",
     "@gorhom/portal": "^1.0.14",
-    "@lezer/common": "^1.5.0",
-    "@lezer/cpp": "^1.1.5",
-    "@lezer/css": "^1.3.0",
-    "@lezer/go": "^1.0.1",
-    "@lezer/highlight": "^1.2.3",
-    "@lezer/html": "^1.3.13",
-    "@lezer/java": "^1.1.3",
-    "@lezer/javascript": "^1.5.4",
-    "@lezer/json": "^1.0.3",
-    "@lezer/markdown": "^1.6.2",
-    "@lezer/php": "^1.0.5",
-    "@lezer/python": "^1.1.18",
-    "@lezer/rust": "^1.0.2",
-    "@lezer/xml": "^1.0.6",
-    "@lezer/yaml": "^1.0.4",
     "@react-native-async-storage/async-storage": "2.2.0",
     "@react-native-masked-view/masked-view": "^0.3.2",
     "@react-native/normalize-colors": "^0.81.5",
@@ -88,7 +74,6 @@
     "expo-system-ui": "~6.0.7",
     "expo-updates": "~29.0.12",
     "expo-web-browser": "~15.0.8",
-    "lezer-elixir": "^1.1.2",
     "lucide-react-native": "^0.546.0",
     "mnemonic-id": "^3.2.7",
     "react": "19.1.4",