BB-399: feat(editor): Add checkbox to copy title language to content language

[atharvsp02]

Problem

When adding or editing Works and Editions, users must manually select the same language twice - once for the title and again for the content language. This can lead to mistakes

Issue link: https://tickets.metabrainz.org/browse/BB-399

Solution

• Checkbox appears for Work and Edition entity types only
• When checked, selecting a title language automatically adds it to content languages
• Prevents adding duplicate languages
• Unified form (cover tab) has checkbox pre-checked to preserve existing behavior
• Users can uncheck to disable auto-copy if needed

Areas of Impact

Modified files:

• name-section/actions.ts - New thunks for checkbox and language sync
• name-section/reducer.js - Added checkbox state
• name-section/name-section.js - Added checkbox UI
• work-section/actions.ts, work-section/reducer.ts - Action type rename
• edition-section/reducer.ts - Added undefined fallback

Behaviors affected:

• Work and Edition entity editors - new checkbox feature
• Unified form - checkbox pre-checked by default

Screenshots:

Before:

After:

Let me know if you have any suggestions or changes you’d like me to make.