docs(legibility): add 18 per-domain README.md files (DOC-6)

Backend (9): document, person, tag, user, geschichte, notification,
ocr, audit, dashboard.
Frontend (8): document, person, tag, user, geschichte, notification,
ocr, shared.
OCR service (1): ocr-service/README.md.

Each README covers: what the domain owns, explicit non-ownership,
public surface (verified by grep against the codebase), internal
layout, and cross-domain dependencies.

Closes #400
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/document/README.md

@@ -0,0 +1,36 @@
+# document (frontend)
+
+UI for the archive's core concept: viewing, uploading, editing, searching, bulk-selecting, and transcribing documents.
+
+## What this domain owns
+
+Components: `DocumentRow`, `DocumentThumbnail`, `DocumentTopBar`, `DocumentViewer`, `DocumentMetadataDrawer`, `DocumentEditLayout`, `DocumentStatusChip`, `UploadZone`, `BulkSelectionBar`, `BulkDropZone`.
+Utilities: `search.ts` (search-param helpers), `filename.ts` (filename formatting), `documentStatusLabel.ts` (i18n label mapping), `validateFile.ts` (upload validation), `groupDocuments.ts` (list grouping).
+Sub-folders: `annotation/`, `transcription/`, `viewer/`.
+
+## What this domain does NOT own
+
+- Person typeahead — `person/PersonTypeahead.svelte` (cross-domain import, allowed by ESLint rule)
+- Tag input — `tag/TagInput.svelte` (cross-domain import, allowed)
+- Shared discussion — `shared/discussion/` (comment/mention editor)
+
+## Key components
+
+| Component                   | Route used in                      | Notes                                |
+| --------------------------- | ---------------------------------- | ------------------------------------ |
+| `DocumentRow.svelte`        | `/` (search results), admin queues | Compact document card with thumbnail |
+| `DocumentViewer.svelte`     | `/documents/[id]`                  | PDF/image inline viewer              |
+| `DocumentEditLayout.svelte` | `/documents/[id]/edit`             | Full edit form with sticky save bar  |
+| `UploadZone.svelte`         | `/documents/new`, bulk upload      | Drag-and-drop file drop area         |
+| `BulkSelectionBar.svelte`   | `/documents` bulk mode             | Multi-select action bar              |
+
+## Cross-domain imports
+
+- `person/PersonTypeahead.svelte` — sender / receiver selection
+- `tag/TagInput.svelte` — tag chip input
+- `ocr/OcrProgress.svelte` — job status indicator in the document header
+- `shared/primitives/BackButton.svelte`, `shared/discussion/` — shared UI
+
+## Backend counterpart
+
+`backend/src/main/java/org/raddatz/familienarchiv/document/README.md`