Add Z.AI, MiMo, OpenRouter and NVIDIA providers

[mondary]

Summary

• Add first-class Z.AI, MiMo, OpenRouter and NVIDIA provider tabs.
• Route Z.AI and MiMo through their configured OpenCode providers.
• Add dynamic provider model catalogs, including OpenRouter public models.
• Add provider icons adapted from CodexBar.
• Filter known retired NVIDIA model entries.

Validation

• Targeted catalog tests passing.
• Production build passing.
• Full test suite previously validated with 1173 tests passing.

Notes

OpenRouter requires each user to configure their own OpenRouter credentials in OpenCode. Z.AI, MiMo and NVIDIA use credentials configured in OpenCode.