Clarify webhook SDK compatibility docs

[taylorjdawson]

Summary

• Focused ENG-4126 follow-up for the currently deployed /features/webhooks/* pages.
• Adds SDK compatibility guidance for createWebhookEndpoint near endpoint creation on /features/webhooks/overview.
• Replaces placeholder troubleshooting with exact SDK versions and differentiated setup/signature failure guidance.

Scope

• Intentionally does not include the larger Add Webhooks V2 docs section #689 Webhooks V2 restructure.
• Does not move pages, add the Add Webhooks V2 docs section #689 reference-section restructure, or add the experimental webhook.site generator.

SDK source of truth

• SDK versions were verified against tkhq/sdk origin/main commit 764965f54.
• @turnkey/sdk-server@6.1.0+ and @turnkey/sdk-browser@6.1.0+ include createWebhookEndpoint.
• @turnkey/crypto@2.10.0+ exports verifyTurnkeyWebhookSignature.

Validation

• jq . docs.json
• git diff --check
• git diff --check HEAD~1..HEAD
• PATH=/Users/taylordawson/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin:$PATH npx mintlify validate

Note: npx mintlify validate fails under the default local Node 25.6.1 because Mintlify rejects Node 25+. It passed when run with the bundled Node 24.14.0 runtime.

[mintlify]

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Project	Status	Preview	Updated (UTC)
turnkey-docs	🟢 Ready	View Preview	Jun 5, 2026, 7:53 PM

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[grahamritter]

looks good to me!