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/admin/users/+layout.server.ts

@@ -1,4 +1,4 @@
-import { createApiClient } from '$lib/api.server';
+import { createApiClient } from '$lib/shared/api.server';
 import type { LayoutServerLoad } from './$types';
 
 export const load: LayoutServerLoad = async ({ fetch }) => {

frontend/src/routes/admin/users/[id]/+page.server.ts

@@ -1,7 +1,7 @@
 import { error, fail, redirect } from '@sveltejs/kit';
 import type { PageServerLoad, Actions } from './$types';
-import { createApiClient } from '$lib/api.server';
-import { getErrorMessage } from '$lib/errors';
+import { createApiClient } from '$lib/shared/api.server';
+import { getErrorMessage } from '$lib/shared/errors';
 
 export const load: PageServerLoad = async ({ params, fetch, locals }) => {
 	const user = locals.user;

frontend/src/routes/admin/users/layout.server.spec.ts

@@ -1,9 +1,9 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+layout.server';
 
-vi.mock('$lib/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
 
-import { createApiClient } from '$lib/api.server';
+import { createApiClient } from '$lib/shared/api.server';
 
 function mockApi(users: unknown[]) {
 	vi.mocked(createApiClient).mockReturnValue({

frontend/src/routes/admin/users/new/+page.server.ts

@@ -1,7 +1,7 @@
 import { error, fail, redirect } from '@sveltejs/kit';
 import type { PageServerLoad, Actions } from './$types';
-import { createApiClient } from '$lib/api.server';
-import { getErrorMessage } from '$lib/errors';
+import { createApiClient } from '$lib/shared/api.server';
+import { getErrorMessage } from '$lib/shared/errors';
 
 export const load: PageServerLoad = async ({ fetch, locals }) => {
 	const user = locals.user;