Update --customer-account-push to support multiple dev instances

[andguy95]

WHY are these changes introduced?

When multiple developers (or the same developer) run dev --customer-account-push concurrently on the same store, the second instance overwrites the Customer Account callback URIs set by the first. This breaks Customer Account sign-in for the first dev server because its tunnel URL is no longer registered as a valid callback URI.

WHAT is this pull request doing?

Removes removeRegex from the push path so that each dev server additively registers its own callback URIs without touching any other session's URLs. The cleanup function (invoked on dev server shutdown) still uses removeRegex to remove only that session's specific URLs.

HOW to test your changes?

1. Run npx shopify hydrogen dev --customer-account-push in a Hydrogen project — confirm Customer Account sign-in works
2. In a separate terminal, start a second dev server with --customer-account-push on the same storefront
3. Verify both servers can sign in via Customer Account (the first should no longer break)
4. Stop the second server — verify the first still works
5. Stop the first server — verify URLs are cleaned up

Unit tests: pnpm vitest packages/cli/src/commands/hydrogen/customer-account/push.test.ts

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or functional changes. Test changes or internal-only config changes do not require a changeset.
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your an-feat-customer-account-push-multiple-urls branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	April 22, 2026 9:54 PM

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