feat: add ZIP archive import button

[FrostyPhoenix2]

Summary

• Adds an Import ZIP button to the home screen alongside Import Chat and Import Folder
• Uses JSZip (already a project dependency) to read the archive and injects files as a boltArtifact chat message — the same mechanism used by Import Folder
• After import, the chat textarea is pre-filled with the install prompt so the user hits Enter once to boot the project

How it works

1. User clicks Import ZIP and selects a .zip file
2. Files are read client-side via JSZip and injected as a bolt message
3. The AI writes files into the WebContainer exactly as it does for freshly built projects
4. If a package.json is detected, the textarea is pre-filled with "Install the dependencies and start the development server."

ZIP format compatibility

• Flat ZIPs (files at root) ✅
• macOS Compress (wraps in one top-level folder) ✅ — prefix stripped automatically
• GitHub Download ZIP (wraps in repo-main/) ✅ — prefix stripped automatically
• node_modules/, .git/, dist/, build folders — skipped automatically

Files changed

• app/utils/zipImport.ts (new) — ZIP parsing, prefix stripping, boltArtifact assembly
• app/components/chat/ImportZipButton.tsx (new) — React button component
• app/components/chat/chatExportAndImport/ImportButtons.tsx — adds button to home screen
• app/components/chat/Chat.client.tsx — pre-fills textarea after import navigation

[FrostyPhoenix2]

Update: Expo/React Native support

Detects Expo projects at import time (checks for app.json, app.config.js, or expo in package.json dependencies)
Strips runnable scripts from package.json so WebContainer doesn't attempt to boot a native project
Shows a code review prompt instead of "install and start dev server" for Expo imports — since WebContainer can't run native mobile code, bolt now summarizes the project instead of hanging indefinitely

Web project behavior is unchanged.