docs(skill): drop remaining paymentRails from create examples

[jklein24]

Summary

Follow-up to the skill spec-refresh (#708). That PR removed the response-only paymentRails field from the create examples in account-types.md, but three references survived elsewhere and contradicted the fix:

• SKILL.md — "paymentRails": ["SPEI"] in the external-account create example
• SKILL.md — Best Practices tip Update all product names to just Grid #10 still asserted "all fiat accounts require paymentRails"
• references/workflows.md — "paymentRails": ["SPEI"] and "paymentRails": ["ACH"] in two create bodies

paymentRails is not an input on any *ExternalAccountCreateInfo schema — Grid selects the rail and returns it on the created account (common/*AccountInfo.yaml). Left as-is, the skill instructs callers to send an invalid field on every fiat account create, and tip #10 is high-weight guidance.

Tip #10 now points at the field that is required (beneficiary) and states the rail is server-selected.

Test plan

Docs-only. Verified no paymentRails remains in any request body across the skill (the 3 surviving mentions all describe it as response-only), and all 25 curl JSON bodies still parse.

Requested by @jklein24

Original PR: #752

[akanter]

• docs(skill): drop remaining paymentRails from create examples #753 👈 (View in Graphite)
• main

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[greptile-apps]

Greptile Summary

      ☠  ⚡  GRIDFORGED RAIL REAPER  ⚡  ☠
     /|\      RIFFS OF THE VOID      /|\
    /_|_\  === CREATE OR PERISH === /_|_\

CRUSH THE INVALID PAYLOADS BENEATH THE IRON RIFF.

• Removes paymentRails from MXN and USD external-account creation examples.
• Replaces the blanket payment-rail requirement with beneficiary guidance and a claim that Grid selects the rail.

Confidence Score: 3/5

The PR should not merge until its external-account creation guidance is reconciled with the OpenAPI schemas that currently require paymentRails.

The changed examples omit paymentRails for MXN and USD create requests, and the new prose explicitly tells users not to send it, while both create schemas still expose it as required.

Files Needing Attention: .claude/skills/grid-api/SKILL.md; .claude/skills/grid-api/references/workflows.md

Important Files Changed

Filename	Overview
.claude/skills/grid-api/SKILL.md	Removes paymentRails from the MXN create example and adds guidance that conflicts with the current OpenAPI create schemas.
.claude/skills/grid-api/references/workflows.md	Removes schema-required paymentRails fields from the documented MXN and USD external-account creation workflows.

Prompt To Fix All With AI

### Issue 1
.claude/skills/grid-api/SKILL.md:580
**Create schemas still require paymentRails**

When users follow the MXN or USD external-account creation guidance, the changed examples omit `paymentRails` and the new text explicitly says not to send it, even though both OpenAPI create schemas mark it as required, causing copied requests to fail schema or API validation.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "docs(skill): drop remaining paymentRails..." | Re-trigger Greptile}

[greptile-apps]

Create schemas still require paymentRails

When users follow the MXN or USD external-account creation guidance, the changed examples omit paymentRails and the new text explicitly says not to send it, even though both OpenAPI create schemas mark it as required, causing copied requests to fail schema or API validation.

Context Used: CLAUDE.md (source)

Prompt To Fix With AI

This is a comment left during a code review.
Path: .claude/skills/grid-api/SKILL.md
Line: 580

Comment:
**Create schemas still require paymentRails**

When users follow the MXN or USD external-account creation guidance, the changed examples omit `paymentRails` and the new text explicitly says not to send it, even though both OpenAPI create schemas mark it as required, causing copied requests to fail schema or API validation.

**Context Used:** CLAUDE.md ([source](https://github.com/lightsparkdev/grid-api/blob/main/CLAUDE.md))

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.