refactor: move lib-root files to lib/shared/ and finalize domain structure

- Move api.server.ts, errors.ts, types.ts, utils.ts, relativeTime.ts to lib/shared/
- Move person relationship components to lib/person/relationship/
- Move Stammbaum components to lib/person/genealogy/
- Move HelpPopover to lib/shared/primitives/
- Update all import paths across routes, specs, and lib files
- Update vi.mock() paths in server-project test files
- Remove now-empty legacy directories (components/, hooks/, server/, etc.)
- Update vite.config.ts coverage include paths for new structure
- Update frontend/CLAUDE.md to reflect domain-based lib/ layout

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

frontend/src/routes/DropZone.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 import { invalidateAll } from '$app/navigation';
 import { m } from '$lib/paraglide/messages.js';
-import { getErrorMessage } from '$lib/errors';
+import { getErrorMessage } from '$lib/shared/errors';
 
 const ACCEPTED_TYPES = ['application/pdf', 'image/jpeg', 'image/png', 'image/tiff'];