[miniflare] Start runtime disposal before browser/proxy cleanup

[teamleaderleo]

Fixes #15085.

Miniflare.dispose() currently waits for browser/proxy cleanup before calling Runtime.dispose(), so either cleanup can delay or skip the workerd termination request.

This starts Runtime.dispose() first, which requests workerd termination before those cleanup awaits. Browser cleanup → exit-hook removal → proxy cleanup keeps the same order.

If browser/proxy cleanup fails, Miniflare.dispose() remembers that error, waits for the already-started runtime exit, continues the remaining cleanup, then returns the cleanup error.

Tests cover:

• requesting workerd termination while proxy cleanup is still pending;
• keeping Miniflare.dispose() pending on a proxy cleanup failure until the runtime exit settles.
• continuing the remaining cleanup after a proxy cleanup failure.

---

• Tests

  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:

• Public documentation

  • Cloudflare docs PR(s):
  • Documentation not necessary because: this changes internal teardown ordering without changing the public API.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 2dc853e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

Name	Type
miniflare	Patch
@cloudflare/deploy-helpers	Patch
@cloudflare/pages-shared	Patch
@cloudflare/remote-bindings	Patch
@cloudflare/runtime-types	Patch
@cloudflare/vite-plugin	Patch
@cloudflare/vitest-pool-workers	Patch
wrangler	Patch

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