Single archive letter: sender → receiver (Unbekannt fallback for empty names,
REQ-014), title, precision date chip via timelineDateLabel (omitted when null,
REQ-013), linking to exactly /documents/{documentId} with no target (REQ-023).
44px touch target enforced inline + focus-visible ring (REQ-020). OCR/import
text via {...} escaping + whitespace-pre-line, no {@html} (REQ-021).
Refs #779
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
