feat: shared supervisor timeline, story assignment and time-spiral view

Each source version is extracted once for every review scope; events carry spans and projects from their sources, and attention density is counted from messages. After publication, events are assigned to project features and sub-threads (cross-project stories only when enabled), with user rename, merge, remove, move and undo. The story graph gains a lazily loaded Three.js time-spiral view. Includes the 3D concept demo, real-data DeepSeek check scripts and docs.

src/shared/contracts.ts

@@ -2225,6 +2225,9 @@ export type DesktopApi = {
     suggestions: (input?: { status?: 'pending' | 'all'; limit?: number; offset?: number }) => Promise<import('./supervision-contracts').SupervisionSuggestion[]>
     suggestionAction: (input: import('./supervision-contracts').SupervisionSuggestionAction) => Promise<import('./supervision-contracts').SupervisionSuggestion>
     retrySuggestions: (input: { heartbeatRunId: string }) => Promise<number>
+    stories: (input: import('./supervision-story-contracts').SupervisionStoryListRequest) => Promise<import('./supervision-story-contracts').SupervisionStoryView>
+    storyAction: (input: import('./supervision-story-contracts').SupervisionStoryAction) => Promise<void>
+    retryStories: (input: { runId: string }) => Promise<import('./supervision-review-contracts').SupervisionReviewProgress>
   }
   experts: {
     list: () => Promise<AssistantExpert[]>