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/relativeTime.spec.ts

@@ -0,0 +1,69 @@
+import { describe, it, expect } from 'vitest';
+import { relativeTimeDe, relativeYearsDe } from './relativeTime';
+
+const NOW = new Date('2026-04-20T12:00:00Z');
+
+describe('relativeTimeDe', () => {
+	it('returns minutes for a gap under one hour', () => {
+		const from = new Date('2026-04-20T11:58:00Z');
+		expect(relativeTimeDe(from, NOW)).toContain('2');
+		expect(relativeTimeDe(from, NOW)).toMatch(/Minute/i);
+	});
+
+	it('returns hours for a gap between 1 and 24 hours', () => {
+		const from = new Date('2026-04-20T09:00:00Z');
+		expect(relativeTimeDe(from, NOW)).toContain('3');
+		expect(relativeTimeDe(from, NOW)).toMatch(/Stunde/i);
+	});
+
+	it('returns days for a gap of 24 hours or more', () => {
+		const from = new Date('2026-04-18T12:00:00Z');
+		expect(relativeTimeDe(from, NOW)).toContain('2');
+		expect(relativeTimeDe(from, NOW)).toMatch(/Tag/i);
+	});
+
+	it('rounds minutes to the nearest whole number', () => {
+		const from = new Date('2026-04-20T11:58:20Z');
+		expect(relativeTimeDe(from, NOW)).toContain('2');
+	});
+
+	it('handles zero gap as 0 minutes', () => {
+		expect(relativeTimeDe(NOW, NOW)).toMatch(/0/);
+		expect(relativeTimeDe(NOW, NOW)).toMatch(/Minute/i);
+	});
+
+	it('falls back to 0 minutes when the input Date is invalid', () => {
+		const invalid = new Date('not-a-real-date');
+		// Never crash the UI if the backend ever ships a malformed uploadedAt.
+		expect(relativeTimeDe(invalid, NOW)).toMatch(/0/);
+		expect(relativeTimeDe(invalid, NOW)).toMatch(/Minute/i);
+	});
+});
+
+describe('relativeYearsDe', () => {
+	it('returns singular "vor 1 Jahr" for exactly one whole year ago', () => {
+		const from = new Date('2025-04-20T12:00:00Z');
+		expect(relativeYearsDe(from, NOW)).toBe('vor 1 Jahr');
+	});
+
+	it('returns plural "vor N Jahren" for more than one year', () => {
+		const from = new Date('1940-04-20T12:00:00Z');
+		expect(relativeYearsDe(from, NOW)).toBe('vor 86 Jahren');
+	});
+
+	it('floors a partial year down (eleven months ago = 0 years)', () => {
+		const from = new Date('2025-06-01T00:00:00Z');
+		// We show "vor weniger als 1 Jahr" rather than rounding up to 1.
+		expect(relativeYearsDe(from, NOW)).toBe('vor weniger als 1 Jahr');
+	});
+
+	it('returns empty string when the input Date is invalid', () => {
+		const invalid = new Date('not-a-real-date');
+		expect(relativeYearsDe(invalid, NOW)).toBe('');
+	});
+
+	it('returns empty string for future dates', () => {
+		const future = new Date('2030-01-01T00:00:00Z');
+		expect(relativeYearsDe(future, NOW)).toBe('');
+	});
+});