Add warning popup when loading LCC files

[slimbuck]

Summary

• Shows an OK/Cancel popup when the user loads an LCC file, advising them to use the /upload page for better publishing to superspl.at
• The popup includes a clickable link to {origin}/upload with a copy-to-clipboard button
• Cancelling the popup aborts the LCC import; clicking OK proceeds as normal
• Added localized warning message for all 9 supported languages (en, de, es, fr, ja, ko, pt-BR, ru, zh-CN)

[Copilot]

Pull request overview

Adds an OK/Cancel warning popup when importing LCC files to guide users toward using the /upload flow for better publishing to superspl.at, including a link users can open/copy.

Changes:

• Prompt with an OK/Cancel popup before proceeding with LCC imports; Cancel aborts the import.
• Provide a /upload link in the popup for quick navigation/copying.
• Add the localized warning string for all supported locales (9 languages).

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/file-handler.ts	Shows an OK/Cancel popup when importing LCC files and aborts import on cancel; includes /upload link.
static/locales/en.json	Adds the new popup.lcc-upload-warning string (English).
static/locales/de.json	Adds the new popup.lcc-upload-warning string (German).
static/locales/es.json	Adds the new popup.lcc-upload-warning string (Spanish).
static/locales/fr.json	Adds the new popup.lcc-upload-warning string (French).
static/locales/ja.json	Adds the new popup.lcc-upload-warning string (Japanese).
static/locales/ko.json	Adds the new popup.lcc-upload-warning string (Korean).
static/locales/pt-BR.json	Adds the new popup.lcc-upload-warning string (Portuguese - Brazil).
static/locales/ru.json	Adds the new popup.lcc-upload-warning string (Russian).
static/locales/zh-CN.json	Adds the new popup.lcc-upload-warning string (Chinese - Simplified).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.