test: fix CI failures from the agent-panel seams

- agentPanel.spec: the bare main.json import crashed Playwright's Node
  loader at collection time, failing every project; add the
  'with { type: json }' attribute (same as WorkflowTabs.test)
- WorkflowTabs.test: mock the agent panel store like the component's
  other stores; its new useAgentPanelStore() call threw no-active-pinia

browser_tests/tests/agent/agentPanel.spec.ts

@@ -4,7 +4,7 @@ import { expect, mergeTests } from '@playwright/test'
 import { comfyPageFixture } from '@e2e/fixtures/ComfyPage'
 import { webSocketFixture } from '@e2e/fixtures/ws'
 
-import enMessages from '@/locales/en/main.json'
+import enMessages from '@/locales/en/main.json' with { type: 'json' }
 import type { AgentWsEvent } from '@/workbench/extensions/agent/schemas/agentApiSchema'
 
 import {

src/components/topbar/WorkflowTabs.test.ts

@@ -79,6 +79,11 @@ vi.mock('@/stores/workspaceStore', () => ({
   useWorkspaceStore: () => ({ shiftDown: false })
 }))
 
+vi.mock('@/workbench/extensions/agent/stores/agent/agentPanelStore', () => ({
+  useAgentPanelStore: () =>
+    reactive({ isOpen: false, enabled: false, toggle: vi.fn() })
+}))
+
 vi.mock('@/utils/mouseDownUtil', () => ({
   whileMouseDown: vi.fn()
 }))