feat: Add Apertis provider support

[theQuert]

Summary

Add Apertis AI as a new LLM provider in OpenCode.

Background

Apertis (https://apertis.ai) is an OpenAI-compatible API provider with 470+ models including:

• Opus 4.5 / Opus 4.5 Thinking
• Sonnet 4.5 / Sonnet 4.5 Thinking
• GPT-5.2 Pro / GPT-5.2 / GPT-5.2 Codex
• Gemini 3 Pro Preview
• Grok Code Fast 1
• GLM 4.7 / GLM 4.7 Thinking
• MiniMax M2.1

Implementation

1. Add Apertis loader in packages/opencode/src/provider/provider.ts
2. Use @ai-sdk/openai-compatible package (already available)
3. Environment variable: APERTIS_API_KEY
4. API base: https://api.apertis.ai/v1

Related

• models.dev PR: feat: Add Apertis LLM provider support models.dev#668

[github-actions]

This issue might be a duplicate of or related to existing issues. Please check:

• [FEATURE]: Use models.dev data for custom providers #9311: [FEATURE]: Use models.dev data for custom providers - proposes automatic model metadata fetching from models.dev for custom providers, which is relevant for aggregator providers like Apertis
• Models from venice provider doesn't work #9108: Models from venice provider doesn't work - documents issues with another OpenAI-compatible aggregator provider (Venice), which may share similar implementation challenges