Add Brainiall provider with 33 AI models

[fasuizu-br]

Summary

Adds Brainiall as a new AI model provider with 33 models across 13 families.

Provider

• API: https://apim-ai-apis.azure-api.net/v1 (OpenAI-compatible)
• Auth: Bearer token (BRAINIALL_API_KEY)
• SDK: @ai-sdk/openai-compatible
• Docs: https://app.brainiall.com

Models (33)

Family	Models	Price Range ($/MTok in/out)
Claude (Anthropic)	Opus 4.6, Sonnet 4.6, Haiku 4.5, Opus 4.5, Sonnet 4.5, 3.5 Haiku, 3 Haiku	$0.25–$75.00
DeepSeek	R1, V3.2	$0.32–$2.50
Llama (Meta)	4 Maverick, 4 Scout, 3.3 70B, 3.1 8B, 3.2 3B, 3.2 1B	$0.02–$0.60
Nova (Amazon)	Premier, Pro, Lite, Micro	$0.035–$12.50
Mistral	Large 3 675B, Devstral 2, Small 3.1 24B	$0.10–$6.00
Qwen	3 235B MoE, 3 32B	$0.35–$1.82
Other	MiniMax M2, Kimi K2.5, Nemotron 70B/30B, GPT OSS 120B, Gemma 27B, Command R+, Palmyra X5, GLM 4.7	$0.03–$15.00

Features

• Prompt caching with cost breakdown for Claude models
• Context windows up to 1M tokens
• Reasoning support (Claude Opus/Sonnet, DeepSeek R1, Nova Premier, Qwen3, Kimi)
• Image input for Claude, Nova, Llama 4, Mistral Large

Notes

This is a clean resubmission replacing #1009, which unintentionally modified files from other providers. This PR only adds files under providers/brainiall/.