test: add duplicate, export, delete and switch app mode E2E scenarios

[Jingyi-Dify]

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Summary

Adds four E2E scenarios covering the core app card operations in the
apps console. All scenarios use the API seeding pattern introduced in
the infrastructure PR (test/e2e-app-management-p1) — no UI flows are
used for preconditions.

• Duplicate: asserts the copy appears in the apps console list
• Export DSL: asserts a .yml file named after the app is
  downloaded; uses expect.poll to handle async blob timing
• Delete: scoped to role="alertdialog" (Base UI), types the app
  name to unlock the confirm button, asserts card disappears
• Switch to Workflow Orchestrate: only available for chat and
  completion modes; seeds a chat app, confirms via role="dialog"
  (Headless UI), asserts navigation to /app/{id}/workflow, and
  captures the new app ID for automatic cleanup

Test plan

• pnpm -C e2e check passes
• Depends on: test/e2e-app-management-p1
• CI E2E covers @apps @core scenarios end-to-end

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Screenshots

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Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods