docs: add Morpheus AI provider

[BowTiedSwan]

Summary

Add documentation for the Morpheus AI provider to the providers directory.

Morpheus AI provides access to enterprise-grade AI models through a unified OpenAI-compatible API gateway, including:

• GLM 4.6 (200K context)
• Kimi K2 Thinking (256K context)
• Qwen3 Coder 480B (262K context)
• Hermes 3 Llama 3.1 405B (128K context)
• Qwen3 235B, Qwen3 Next 80B
• Llama 3.3 70B
• Mistral 31 24B
• Venice Uncensored
• Qwen3 4B, Llama 3.2 3B, Hermes 4 14B

The provider is already configured and working via custom configuration. Adding it to the official provider list will make it easier for users to discover and use.

Changes

• Added Morpheus AI provider section to providers.mdx
• Included basic setup instructions
• Added example config for additional models

Related Links

• Morpheus AI: https://mor.org
• API Documentation: https://apidocs.mor.org/api-reference/introduction