feat(person): render precise life dates on cards, hover card, and mention dropdown

Cards compose aria-hidden * / † glyphs in markup so screen readers only
announce the dates; PersonSummaryDTO list card stays year-shaped by
design (ADR-039). MentionDropdown subtitle wraps instead of truncating
so DAY-precision ranges fit at 320px.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/lib/shared/discussion/MentionDropdown.svelte

@@ -306,6 +306,12 @@ function selectItem(item: Person) {
 		</a>
 	{:else}
 		{#each model.items as person, i (person.id)}
+			{@const lifeDates = formatLifeDateRange(
+				person.birthDate,
+				person.birthDatePrecision,
+				person.deathDate,
+				person.deathDatePrecision
+			)}
 			<div
 				class={[
 					'flex min-h-[44px] cursor-pointer flex-col gap-1 px-3 py-2.5 text-left hover:bg-canvas',
@@ -325,9 +331,11 @@ function selectItem(item: Person) {
 				}}
 			>
 				<span class="truncate font-serif text-base text-ink">{person.displayName}</span>
-				{#if formatLifeDateRange(person.birthYear, person.deathYear)}
-					<span class="truncate font-sans text-xs text-ink-3">
-						{formatLifeDateRange(person.birthYear, person.deathYear)}
+				{#if lifeDates}
+					<!-- whitespace-normal: a DAY-precision range (~37 chars) wraps to a second
+					     line at 320px instead of being clipped by truncate. -->
+					<span class="font-sans text-xs whitespace-normal text-ink-3">
+						{lifeDates}
 					</span>
 				{/if}
 			</div>

frontend/src/lib/shared/discussion/MentionDropdown.svelte.test.ts

@@ -103,11 +103,18 @@ describe('MentionDropdown', () => {
 		expect(option?.getAttribute('aria-selected')).toBe('true');
 	});
 
-	it('renders the life-date range when birthYear or deathYear is present', async () => {
+	it('renders the life-date range when birth or death date is present', async () => {
 		render(MentionDropdown, {
 			props: {
 				model: baseModel({
-					items: [makePerson('p1', 'Anna', { birthYear: 1899, deathYear: 1972 })]
+					items: [
+						makePerson('p1', 'Anna', {
+							birthDate: '1899-01-01',
+							birthDatePrecision: 'YEAR',
+							deathDate: '1972-01-01',
+							deathDatePrecision: 'YEAR'
+						})
+					]
 				})
 			}
 		});
@@ -115,6 +122,25 @@ describe('MentionDropdown', () => {
 		await expect.element(page.getByText(/1899/)).toBeVisible();
 	});
 
+	it('renders a DAY-precision birth date as a full date without clipping it away', async () => {
+		render(MentionDropdown, {
+			props: {
+				model: baseModel({
+					items: [
+						makePerson('p1', 'Anna', {
+							birthDate: '1901-03-14',
+							birthDatePrecision: 'DAY',
+							deathDate: '1944-11-02',
+							deathDatePrecision: 'DAY'
+						})
+					]
+				})
+			}
+		});
+
+		await expect.element(page.getByText(/14\. März 1901/)).toBeVisible();
+	});
+
 	it('falls back to a default position when clientRect returns null', async () => {
 		render(MentionDropdown, {
 			props: {

frontend/src/lib/shared/discussion/PersonMentionEditor.svelte.spec.ts

@@ -35,8 +35,10 @@ const AUGUSTE: Person = {
 	personType: 'PERSON',
 	familyMember: false,
 	provisional: false,
-	birthYear: 1882,
-	deathYear: 1944
+	birthDate: '1882-01-01',
+	birthDatePrecision: 'YEAR',
+	deathDate: '1944-01-01',
+	deathDatePrecision: 'YEAR'
 };
 
 const ANNA: Person = {
@@ -47,7 +49,8 @@ const ANNA: Person = {
 	personType: 'PERSON',
 	familyMember: false,
 	provisional: false,
-	birthYear: 1860
+	birthDate: '1860-01-01',
+	birthDatePrecision: 'YEAR'
 };
 
 function mockFetchWithPersons(persons: Person[] = [AUGUSTE, ANNA]) {