feat(timeline): add eventCardConfig accent matrix + DTO test factories

getAccentConfig(entry) maps each EVENT to its glyph (* / † / ⚭ / ★ / ◍), German
redundant-cue label, and accent kind (REQ-007/008/018). test-factories build
TimelineEntryDTO/TimelineDTO mirroring the real wire shape for component specs.

Refs #779
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/timeline/test-factories.ts

@@ -0,0 +1,34 @@
+import type { components } from '$lib/generated/api';
+
+type TimelineEntryDTO = components['schemas']['TimelineEntryDTO'];
+type TimelineYearDTO = components['schemas']['TimelineYearDTO'];
+type TimelineDTO = components['schemas']['TimelineDTO'];
+
+/**
+ * Builds a `TimelineEntryDTO` mirroring the real wire shape (no `year`,
+ * `description`, or `snippet` fields). Defaults to a dated DAY-precision letter;
+ * override `kind`/`derived`/`type`/`derivedType` etc. for events.
+ */
+export function makeEntry(overrides: Partial<TimelineEntryDTO> = {}): TimelineEntryDTO {
+	return {
+		kind: 'LETTER',
+		precision: 'DAY',
+		derived: false,
+		senderName: 'Karl Raddatz',
+		receiverName: 'Elfriede Raddatz',
+		eventDate: '1915-06-15',
+		title: 'Brief aus dem Feld',
+		documentId: '11111111-1111-1111-1111-111111111111',
+		...overrides
+	};
+}
+
+export function makeYear(year: number, entries: TimelineEntryDTO[]): TimelineYearDTO {
+	return { year, entries };
+}
+
+export function makeTimelineDTO(
+	opts: { years?: TimelineYearDTO[]; undated?: TimelineEntryDTO[] } = {}
+): TimelineDTO {
+	return { years: opts.years ?? [], undated: opts.undated ?? [] };
+}