Adds eslint-plugin-boundaries with one element type per Tier-1 domain and an
explicit allow-list encoding the architectural dependency graph:
- document may import from: shared, person, tag, ocr, activity, conversation
- geschichte may import from: shared, person, document
- ocr may import from: shared, document
- activity may import from: shared, notification
- all others (person, tag, user, notification, conversation): shared only
- routes may import from any domain
Default is 'disallow', so any unlisted cross-domain import is an error.
Two eslint-disable-next-line comments remain in shared/discussion where
person-domain helpers (getInitials, formatLifeDateRange) are needed to render
participant metadata; moving them to shared would lose the person-type context.
Closes#410
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>