chore(repo): remove leftover keyless creation code

[djgould]

Final PR of the keyless-removal stack (#9517 → #9575 → #9576 → #9578). Deletes everything the earlier PRs orphaned; the only keyless code left is the claimed-app flow (read stored keys, complete onboarding, nextjs prompt) and the *_KEYLESS_DISABLED flags.

• @clerk/shared/keyless: deletes resolveKeysWithKeylessFallback, getOrCreateKeys, logKeylessMessage, createKeylessModeMessage, KeylessResult, PublicKeylessApplication; KeylessAPI is completion-only.
• @clerk/backend: removes experimental createAccountlessApplication (no SDK mints anymore).
• @clerk/nextjs: deletes the unused keyless cookie reader (server/keyless.ts) and only-try.ts; drops the dead keylessMode params from decorateRequest/encryptClerkRequestData; collapses the constant-true runningWithClaimedKeys branches; claimed onboarding now delegates to the shared helper; logs a pointer to existing .clerk/.tmp/keyless.json keys before the missing-key error (parity with the other SDKs).
• Integration: keylessHelpers reduced to mockClaimedInstanceEnvironmentCall; stale waitForServer comment fixed.

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Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Ready	Preview	Aug 26, 2026 5:06pm
swingset	Ready	Preview	Aug 26, 2026 5:06pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 6417811

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

This PR includes changesets to release 23 packages

Name	Type
@clerk/shared	Minor
@clerk/nextjs	Patch
@clerk/backend	Minor
@clerk/astro	Patch
@clerk/chrome-extension	Patch
@clerk/clerk-js	Patch
@clerk/electron	Patch
@clerk/expo-passkeys	Patch
@clerk/expo	Patch
@clerk/express	Patch
@clerk/fastify	Patch
@clerk/headless	Patch
@clerk/hono	Patch
@clerk/localizations	Patch
@clerk/msw	Patch
@clerk/nuxt	Patch
@clerk/react-router	Patch
@clerk/react	Patch
@clerk/tanstack-react-start	Patch
@clerk/testing	Patch
@clerk/ui	Patch
@clerk/vue	Patch
@clerk/swingset	Patch

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