chore(api): regenerate types with TimelineEntryDTO.linkedEventId

Regenerated frontend/src/lib/generated/api.ts from the live OpenAPI spec after
adding the nullable linkedEventId field — keeps the CI type-check green for the
#827 grouping UI that consumes it.

Refs #827
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/generated/api.ts

@@ -2467,6 +2467,8 @@ export interface components {
             rootTagId?: string;
             rootTagName?: string;
             rootTagColor?: string;
+            /** Format: uuid */
+            linkedEventId?: string;
         };
         TimelineYearDTO: {
             /** Format: int32 */