Story 31: View Upcoming Stories

Add GET /workflow/upcoming endpoint that reads .story_kit/stories/upcoming/
and returns story IDs with names parsed from frontmatter. Add UpcomingPanel
component wired into Chat view with loading, error, empty, and list states.

12 new tests (3 backend, 9 frontend) all passing.

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

frontend/src/api/workflow.ts

@@ -62,6 +62,15 @@ export interface ReviewListResponse {
 	stories: ReviewStory[];
 }
 
+export interface UpcomingStory {
+	story_id: string;
+	name: string | null;
+}
+
+export interface UpcomingStoriesResponse {
+	stories: UpcomingStory[];
+}
+
 const DEFAULT_API_BASE = "/api";
 
 function buildApiUrl(path: string, baseUrl = DEFAULT_API_BASE): string {
@@ -124,6 +133,13 @@ export const workflowApi = {
 	getReviewQueueAll(baseUrl?: string) {
 		return requestJson<ReviewListResponse>("/workflow/review/all", {}, baseUrl);
 	},
+	getUpcomingStories(baseUrl?: string) {
+		return requestJson<UpcomingStoriesResponse>(
+			"/workflow/upcoming",
+			{},
+			baseUrl,
+		);
+	},
 	ensureAcceptance(payload: AcceptanceRequest, baseUrl?: string) {
 		return requestJson<boolean>(
 			"/workflow/acceptance/ensure",