test: fix CI coverage + e2e for user/message coalescing

- tui.spec: exercise a goal-sourced injected context card (labels by
  source kind, not plugin name), closing the last uncovered branch in
  tui/src/index.ts that the CI coverage gate caught.
- time-context.e2e / goal.e2e: filter injected context by source now
  that it is a user/message (plugin/goal source), and count goal
  continuation rounds by round>0 rather than event type.

packages/context/time-context/tests/time-context.e2e.ts

@@ -48,7 +48,8 @@ describe('time-context through a real headless cordis.yml', () => {
     expect(stderr).not.toContain('UNHANDLED')
     expect(events.filter(event => event.type === 'turn/end')).toHaveLength(2)
 
-    const contexts = events.filter(event => event.type === 'user/message')
+    const contexts = events.filter(
+      (event): event is SessionEvent<'user/message'> => event.type === 'user/message' && event.data.source.kind === 'plugin')
     const starts = events.filter(event => event.type === 'step/start')
     expect(contexts).toHaveLength(2)
     expect(starts).toHaveLength(2)