gh-aw install-order test still asserts worker-first after dispatcher-first rollout #1878

Problem

PR #1874 deliberately changed every live gh aw add surface to install the dispatcher first because current gh-aw dependency discovery compiles the dispatcher before confirming the explicit worker/reviewer surface. The guide now correctly says:

Keep the dispatcher first.

But test/gh-aw-implement-workflow.test.ts still asserts the old worker-first contract:

expect(dispatcherIndex).toBeGreaterThan(workerIndex);
expect(guide).toContain('The single command installs the dedicated worker first');

On current dev (08b89daa when measured), the guide indices are dispatcher=875, worker=920, so the full suite fails with expected 875 to be greater than 920.

This is not a #1605 regression: PR #1877 independently reproduces the same failure against origin/dev. It currently blocks that otherwise-repaired PR.

Acceptance criteria

• Update the install-order test to enforce the current dispatcher-first contract.
• Assert the current explanatory prose (gh aw add discovers worker/reviewer dependencies while compiling the dispatcher), not the removed worker-first sentence.
• Verify all three install surfaces remain in coherent order: dispatcher, implementation worker, reviewer.
• Mutation-check reversing dispatcher/worker or worker/reviewer order makes the test fail.
• Run the focused workflow test and full relevant CI.

Scope

Test correction only unless current dev reveals another stale worker-first assertion. Do not change the verified dispatcher-first installation behavior delivered by #1874.