fix(canvas): add liveAnnouncement to makeStore test helper

Fixes TS2339 in canvas-events.test.ts where the liveAnnouncement
accessor was missing from the makeStore() mock state. The store
defines liveAnnouncement at canvas.ts:336 but the test helper
omitted it, causing TypeScript to reject state.liveAnnouncement
in the liveAnnouncement describe block (lines 843–1012).

Change: added `liveAnnouncement = ""` parameter and property to
makeStore() so the mock state matches the real store shape.

[core-fe-agent]
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

canvas/src/store/__tests__/canvas-events.test.ts

@@ -52,9 +52,10 @@ function makeStore(
   nodes: Node<WorkspaceNodeData>[] = [],
   edges: Edge[] = [],
   selectedNodeId: string | null = null,
-  agentMessages: Record<string, Array<{ id: string; content: string; timestamp: string }>> = {}
+  agentMessages: Record<string, Array<{ id: string; content: string; timestamp: string }>> = {},
+  liveAnnouncement = ""
 ) {
-  const state = { nodes, edges, selectedNodeId, agentMessages };
+  const state = { nodes, edges, selectedNodeId, agentMessages, liveAnnouncement };
   const get = () => state;
   const set = vi.fn((partial: Record<string, unknown>) => {
     Object.assign(state, partial);