[Docs] Add Requesty to inference provider docs

[roomote-community]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote, in the web UI, or in Discord.

What changed

• added Requesty to the inference provider overview and navigation
• added a Requesty setup guide covering API keys, model IDs, costs, verification, and troubleshooting
• documented REQUESTY_API_KEY in the centralized environment-variable table and Requesty in the runtime-forwarding provider list
• connected the setup wizard's Requesty selection to the new guide and covered the mapping with a test
• added the supplied Requesty mark as a local grayscale asset

Why this change was made

Requesty is available as an inference provider, but the public provider list and setup help did not document it. This keeps the provider guide, centralized configuration references, and setup experience aligned with the selectable provider catalog.

Impact

Operators can find Requesty in the inference provider documentation, identify its supported environment variable, and follow provider-specific setup guidance from both the docs site and setup wizard.

Screenshots

[roomote-community]

No code issues found. See task

• apps/docs/providers/inference/requesty.mdx:21 Add REQUESTY_API_KEY to the centralized Environment Variables table and add Requesty to the runtime-forwarding list in models.mdx. This new guide tells env-based users to set the key, while models.mdx links to that table as the complete supported-key list, where Requesty is still absent.

_{Reviewed c344ce3}

[roomote-community]

Fixed in c344ce3: added REQUESTY_API_KEY to the centralized Environment Variables table and Requesty to the runtime-forwarding list in models.mdx. Docs validation and broken-link checks pass. See task.