refactor(person): delete personAvatarColor + djb2 from personFormat.ts

Dead code now that all callers use Avatar / avatarFor. Removes the old
5-color id-hashed palette (AVATAR_PALETTE) and its test suite.

Refs #855
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/person/personFormat.spec.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest';
-import { getInitials, abbreviateName, formatXsMeta, personAvatarColor } from './personFormat';
+import { getInitials, abbreviateName, formatXsMeta } from './personFormat';
 import { formatDate } from '$lib/shared/utils/date';
 
 // ─── getInitials ─────────────────────────────────────────────────────────────
@@ -97,29 +97,6 @@ describe('formatXsMeta', () => {
 	});
 });
 
-// ─── personAvatarColor ───────────────────────────────────────────────────────
-
-const PALETTE = ['#012851', '#5A3080', '#007596', '#2A6040', '#803020'];
-
-describe('personAvatarColor', () => {
-	it('returns a value from the palette', () => {
-		expect(PALETTE).toContain(personAvatarColor('abc'));
-	});
-
-	it('is deterministic — same id always returns same color', () => {
-		const id = '550e8400-e29b-41d4-a716-446655440000';
-		expect(personAvatarColor(id)).toBe(personAvatarColor(id));
-	});
-
-	it('all 5 palette entries are reachable across 1000 random UUIDs', () => {
-		const seen = new Set<string>();
-		for (let i = 0; i < 1000; i++) {
-			seen.add(personAvatarColor(crypto.randomUUID()));
-		}
-		expect(seen.size).toBe(5);
-	});
-});
-
 // ─── formatDate ──────────────────────────────────────────────────────────────
 
 describe('formatDate', () => {

frontend/src/lib/person/personFormat.ts

@@ -8,16 +8,6 @@ type DocForMeta = {
 	documentDate?: string | null;
 };
 
-const AVATAR_PALETTE = ['#012851', '#5A3080', '#007596', '#2A6040', '#803020'] as const;
-
-function djb2(str: string): number {
-	let hash = 5381;
-	for (let i = 0; i < str.length; i++) {
-		hash = (hash * 33) ^ str.charCodeAt(i);
-	}
-	return Math.abs(hash);
-}
-
 /** Localized fallback when a person has no name parts. */
 export function unknownPersonName(): string {
 	return m.person_unknown();
@@ -83,7 +73,3 @@ export function formatXsMeta(doc: DocForMeta): string {
 
 	return parts.join(' · ');
 }
-
-export function personAvatarColor(personId: string): string {
-	return AVATAR_PALETTE[djb2(personId) % AVATAR_PALETTE.length];
-}