Embedded signing docs list a NotSignersTurn 409 the API never returns #213

Related PRs

• docs(turbosign): drop NotSignersTurn, the API only returns RecipientNotInTurn #217 (docs: drop NotSignersTurn from the embedded signing pages)
• fix(skill): create_signing_url never throws NotSignersTurn quickstart#35 (QuickStart skill python.md)

What's wrong

The docs say createSigningUrl can return HTTP 409 NotSignersTurn:

• docs/TurboSign/embedded-signing/build/sequential-signers.md:60 and :415, plus the retry code in all six language tabs (lines 90, 133, 188, 233, 277, 308)
• embedded-signing/index.md:125
• embedded-signing/reference.md:247 and :535

The API's only turn refusal is RecipientNotInTurn: the eligibility check defines only RecipientAlreadySigned and RecipientNotInTurn, and createSigningUrl throws only that code. NotSignersTurn exists only as an unused status mapping in the backend; nothing throws it.

Impact

Developers write and test handling for a code that never arrives, and the error tables list a response they'll never see.

Suggested fix

• Remove NotSignersTurn from the error tables and prose.
• In code samples, either drop it or keep it with a comment ("reserved; the current API returns only RecipientNotInTurn"). The SDKs keep it on purpose for cross-SDK parity, so no SDK change.
• Same fix in the QuickStart skill, skills/turbodocx-sdk/references/python.md:451, which says create_signing_url throws NotSignersTurn.

Severity: S3. Found while building the kiosk how-to video; verified against the backend and Docs origin/main.