When users try to import custom example images without configuring the
download location, show a helpful guidance interface instead of failing
silently or showing an error after the fact.
Changes:
- ShowcaseView.js: Check if example_images_path is configured before
showing import interface; display setup guidance with open settings button
- showcase.css: Add styles for the setup guidance state
- locales: Add translation keys for all 10 supported languages
Clicking 'Open Settings' will:
1. Open the settings modal
2. Scroll to the Example Images section
3. Highlight the section with a brief animation
4. Focus the input field
Fixes#785
Will Miao
a78868adce