Add Phala inference provider

[Marvin-Cypher]

Summary

• Add a Phala Inference Provider helper for OpenAI-compatible conversational models
• Register provider id phala in the inference provider registry and type list
• Map provider id phala to the PhalaCloud Hub organization
• Add Phala to the inference package provider README

Notes

• Production API base URL: https://api.redpill.ai
• Hub organization: https://huggingface.co/PhalaCloud
• Provider mapping endpoint is expected to be /api/partners/phala/models, but currently returns 404 until Hugging Face enables the provider server-side.

Test Plan

• pnpm --dir packages/inference run check
• pnpm --dir packages/inference run format:check