v0.7.0: Fix broken image display

What's Fixed

Images loaded and graded correctly but showed broken image icons in the UI. The root cause was that Tauri's convertFileSrc() generates asset:// protocol URLs to serve local files, but:

1. The protocol-asset Cargo feature was not enabled on the tauri dependency
2. The assetProtocol scope was not configured in tauri.conf.json

Without these, the asset protocol handler was never registered, so all image URLs failed to resolve in the webview.

Changes

• Enabled protocol-asset feature in src-tauri/Cargo.toml
• Added assetProtocol scope configuration in tauri.conf.json to allow serving local files
• Bumped version to 0.7.0