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/lib/shared/discussion/CommentThread.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 import { onMount, untrack } from 'svelte';
 import { m } from '$lib/paraglide/messages.js';
-import type { Comment, FlatMessage, MentionDTO } from '$lib/types';
+import type { Comment, FlatMessage, MentionDTO } from '$lib/shared/types';
 import MentionEditor from '$lib/shared/discussion/MentionEditor.svelte';
 import CommentMessage from '$lib/shared/discussion/CommentMessage.svelte';
 import { extractContent } from '$lib/shared/discussion/mention';