docs: add HPC-AI integration

[lioZ129]

Summary

Adds documentation for integrating HPC-AI (OpenAI-compatible Model APIs) with Portkey: LLM integration page, guides quickstart, navigation, LLM index card, and Model Catalog / OpenAPI copy updates for the hpc-ai provider slug.

Changes

• integrations/llms/hpc-ai.mdx — Main integration doc: Model Catalog (@hpc-ai), Portkey SDK and OpenAI client examples, cURL, self-hosted gateway headers, and links to HPC-AI.
• guides/integrations/hpc-ai.mdx — Shorter guide: OpenAI client + createHeaders quickstart and link to the full integration page.
• docs.json — Register HPC-AI under integrations LLMs and guides.
• integrations/llms.mdx — New HPC-AI card on the LLM integrations index.
• product/model-catalog/portkey-models.mdx — Include hpc-ai in provider slug examples.
• openapi/portkey-models.json — Include hpc-ai in the supported-providers description text.

Test plan

• Preview docs build; open /integrations/llms/hpc-ai and /guides/integrations/hpc-ai.
• Confirm sidebar/nav shows HPC-AI where expected.

[Copilot]

Pull request overview

Adds documentation and navigation entries for integrating the HPC-AI OpenAI-compatible Model APIs with Portkey, and updates provider slug references across the docs and OpenAPI copy.

Changes:

• Added new HPC-AI integration page (/integrations/llms/hpc-ai) with SDK/OpenAI client/cURL examples and Model Catalog setup steps.
• Added a shorter HPC-AI guide quickstart and registered both pages in docs.json navigation.
• Updated provider slug examples in the Model Catalog docs and “Supported Providers” copy in the Models OpenAPI spec.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
product/model-catalog/portkey-models.mdx	Adds hpc-ai to provider slug examples for pricing/config endpoints.
openapi/portkey-models.json	Adds hpc-ai to the “Supported Providers” description text.
integrations/llms/hpc-ai.mdx	New full HPC-AI integration doc with quickstart and self-hosted gateway notes.
integrations/llms.mdx	Adds HPC-AI card to the LLM integrations index.
guides/integrations/hpc-ai.mdx	New shorter HPC-AI guide using OpenAI client + createHeaders.
docs.json	Registers the new HPC-AI integration + guide pages in nav.

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