feat: add Avian as an LLM inference provider

[avianion]

Summary

Add Avian as a new OpenAI-compatible LLM inference provider with affordable pricing for frontier open-source models.

Provider Details

• API Base URL: https://api.avian.io/v1
• Auth: Bearer token via AVIAN_API_KEY environment variable
• Type: openai-compat (standard OpenAI-compatible chat completions, streaming, function calling)

Models

Model	Context	Max Output	Input $/1M	Output $/1M
deepseek/deepseek-v3.2	164K	65K	$0.26	$0.38
moonshotai/kimi-k2.5	131K	8K	$0.45	$2.20
z-ai/glm-5	131K	16K	$0.30	$2.55
minimax/minimax-m2.5	1M	1M	$0.30	$1.10

Changes

• Add internal/providers/configs/avian.json with provider config and model definitions
• Register the Avian provider in internal/providers/providers.go
• Add InferenceProviderAvian constant in pkg/catwalk/provider.go

Usage

export AVIAN_API_KEY=your-key-here
crush --model avian/deepseek/deepseek-v3.2

cc @kujtimiihoxha @caarlos0

[avianion]

Friendly follow-up — this PR is still active and ready for review. Would appreciate a look when you get a chance! cc @andreynering

[avianion]

Friendly follow-up — this PR is still active and ready for review. All feedback has been addressed. Would appreciate a look when you get a chance! cc @andreynering

[avianion]

Hey @andreynering — friendly follow-up on this PR. Avian is an OpenAI-compatible inference provider that's already live and powering apps like ISEKAI ZERO. This is a lightweight integration (standard OpenAI-compatible endpoint) and we're happy to address any feedback or make adjustments. Would love to get this merged if you have a moment to review. Thanks!