feat(person): generation dropdown on Person edit/new forms (#689)

PersonEditForm.svelte gains a G 0…G 6 select inside the {#if isPerson}
block. min-h-[44px] meets WCAG 2.5.8 / dual-audience touch target.
generationStr is initialised via $state(untrack(...)) so prop reruns
never reset an in-progress edit (same pattern as selectedType).

Both /persons/[id]/edit and /persons/new form actions read the field
without the conditional-spread idiom — generation always lands in the
PUT/POST body. G 0 is a valid family-tree-root value the spread would
silently drop, and an empty option sends null so a human can clear the
field back to "unset".

i18n adds person_label_generation / person_option_generation_unset /
person_hint_generation in de/en/es. Drops the dead stammbaum_generations
key (zero callsites after the filter-chip removal in the spec).

Tests: dropdown render + hydration in the component, generation=0/3/null
arriving in the API body in the server actions.

Refs #689

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/routes/persons/[id]/edit/page.server.spec.ts

@@ -0,0 +1,99 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
+
+import { createApiClient } from '$lib/shared/api.server';
+import { actions } from './+page.server';
+
+const mockFetch = vi.fn() as unknown as typeof fetch;
+
+beforeEach(() => vi.clearAllMocks());
+
+function makeFormData(overrides: Partial<Record<string, string>> = {}): {
+	request: Request;
+	redirectThrown: () => unknown;
+} {
+	const fd = new FormData();
+	fd.set('personType', 'PERSON');
+	fd.set('firstName', 'Hans');
+	fd.set('lastName', 'Müller');
+	for (const [k, v] of Object.entries(overrides)) {
+		if (v == null) fd.delete(k);
+		else fd.set(k, v);
+	}
+	return {
+		request: new Request('http://localhost/persons/p1/edit', { method: 'POST', body: fd }),
+		redirectThrown: () => {}
+	};
+}
+
+describe('persons/[id]/edit update action — generation (#689)', () => {
+	it('always includes generation in the PUT body — even when value is 0', async () => {
+		const put = vi
+			.fn()
+			.mockResolvedValue({ response: { ok: true, status: 200 }, data: { id: 'p1' } });
+		vi.mocked(createApiClient).mockReturnValue({ PUT: put } as unknown as ReturnType<
+			typeof createApiClient
+		>);
+
+		const { request } = makeFormData({ generation: '0' });
+
+		try {
+			// eslint-disable-next-line @typescript-eslint/no-explicit-any
+			await actions.update({ request, params: { id: 'p1' }, fetch: mockFetch } as any);
+		} catch {
+			// redirect throws on success — ignore
+		}
+
+		expect(put).toHaveBeenCalledTimes(1);
+		const body = put.mock.calls[0][1].body;
+		expect(body).toHaveProperty('generation', 0);
+	});
+
+	it('sends generation: null when the dropdown is cleared (empty option)', async () => {
+		const put = vi
+			.fn()
+			.mockResolvedValue({ response: { ok: true, status: 200 }, data: { id: 'p1' } });
+		vi.mocked(createApiClient).mockReturnValue({ PUT: put } as unknown as ReturnType<
+			typeof createApiClient
+		>);
+
+		const { request } = makeFormData({ generation: '' });
+
+		try {
+			// eslint-disable-next-line @typescript-eslint/no-explicit-any
+			await actions.update({ request, params: { id: 'p1' }, fetch: mockFetch } as any);
+		} catch {
+			// redirect throws on success — ignore
+		}
+
+		expect(put).toHaveBeenCalledTimes(1);
+		const body = put.mock.calls[0][1].body;
+		expect(body).toHaveProperty('generation', null);
+	});
+
+	it('sends generation: 3 when the dropdown carries G 3', async () => {
+		const put = vi
+			.fn()
+			.mockResolvedValue({ response: { ok: true, status: 200 }, data: { id: 'p1' } });
+		vi.mocked(createApiClient).mockReturnValue({ PUT: put } as unknown as ReturnType<
+			typeof createApiClient
+		>);
+
+		const { request } = makeFormData({ generation: '3' });
+
+		try {
+			// eslint-disable-next-line @typescript-eslint/no-explicit-any
+			await actions.update({ request, params: { id: 'p1' }, fetch: mockFetch } as any);
+		} catch {
+			// redirect throws on success — ignore
+		}
+
+		expect(put).toHaveBeenCalledTimes(1);
+		const body = put.mock.calls[0][1].body;
+		expect(body).toHaveProperty('generation', 3);
+	});
+});