test(persons): expand CoCorrespondentsList coverage

Adds single-word name (one-initial) and leading-space edge cases
for the initials function.

2 new tests covering ~4 branches.

Refs #496.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/persons/[id]/CoCorrespondentsList.svelte.test.ts

@@ -70,4 +70,30 @@ describe('CoCorrespondentsList', () => {
 
 		await expect.element(page.getByText('MM')).toBeVisible();
 	});
+
+	it('handles a single-word name (initials use just one letter)', async () => {
+		render(CoCorrespondentsList, {
+			props: {
+				coCorrespondents: [{ id: 'c-1', name: 'Cher', count: 2 }],
+				personId: 'p-1'
+			}
+		});
+
+		// "Cher" → initials "C"
+		const initialsBadge = document.querySelector('span.flex.h-4.w-4');
+		expect(initialsBadge?.textContent?.trim()).toBe('C');
+	});
+
+	it('handles a name part starting with empty string gracefully', async () => {
+		render(CoCorrespondentsList, {
+			props: {
+				coCorrespondents: [{ id: 'c-1', name: '  Max', count: 1 }],
+				personId: 'p-1'
+			}
+		});
+
+		// Leading space → name.split(' ') yields ['', '', 'Max']; first chars are '', '', 'M' → 'M'
+		const initialsBadge = document.querySelector('span.flex.h-4.w-4');
+		expect(initialsBadge?.textContent?.trim()).toContain('M');
+	});
 });