feat: add Script Builder page with chat UI, code blocks, preview modal, and save dialog

- ScriptCodeBlock: collapsed code preview with syntax highlighting (first 5 lines)
- ScriptBuilderInput: auto-resize chat input with Enter-to-send
- ScriptBuilderChat: message list with markdown rendering and code blocks
- ScriptPreviewModal: fullscreen script viewer with line numbers
- SaveToLibraryDialog: save script with name, description, category, team sharing
- ScriptBuilderPage: language selector, session management, FlowPilot handoff
- Added route, sidebar nav item (fuchsia), and mobile nav entry

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

frontend/package.json

@@ -31,6 +31,7 @@
     "@sentry/vite-plugin": "^5.1.1",
     "@stripe/stripe-js": "^8.7.0",
     "@tailwindcss/vite": "^4.2.1",
+    "@types/react-syntax-highlighter": "^15.5.13",
     "@xyflow/react": "^12.10.0",
     "axios": "^1.13.4",
     "class-variance-authority": "^0.7.1",
@@ -46,6 +47,7 @@
     "react-helmet-async": "^3.0.0",
     "react-markdown": "^10.1.0",
     "react-router-dom": "^7.13.0",
+    "react-syntax-highlighter": "^16.1.1",
     "recharts": "^3.7.0",
     "sonner": "^2.0.7",
     "tailwind-merge": "^3.4.0",
@@ -62,8 +64,8 @@
     "@types/node": "^24.10.9",
     "@types/react": "^19.2.5",
     "@types/react-dom": "^19.2.3",
-    "@vitest/coverage-v8": "^4.0.18",
     "@vitejs/plugin-react": "^5.1.1",
+    "@vitest/coverage-v8": "^4.0.18",
     "eslint": "^9.39.1",
     "eslint-plugin-react-hooks": "^7.0.1",
     "eslint-plugin-react-refresh": "^0.4.24",