Enhance client.models with capability filtering from /v1/models

[flyworker]

Context

mega-nova-api is implementing enhanced GET /v1/models (MeganovaAI/mega-nova-api#442) with per-model capabilities (chat, embedding, image, video, tool_calling). The SDK should expose this.

Current State

• client.models.list() returns List[ModelInfo] with basic fields
• No capability filtering

Requirements

• Add capabilities field to ModelInfo model
• Add client.models.list(capability='chat') filter parameter
• Add client.models.get(model_id) for single model detail
• Update ModelInfo Pydantic model with new fields:

  class ModelInfo(BaseModel):
      id: str
      name: str
      description: Optional[str]
      context_length: Optional[int]
      capabilities: List[str]  # ['chat', 'tools', 'vision', 'embedding']
      pricing: Optional[ModelPricing]

Depends On

• mega-nova-api#442 (models endpoint)

[flyworker]

📋 Reference Report: AI API Compatibility Best Practices Research (29 items, 7 categories — protocols, gateways, SDKs, cloud platforms, local inference)

Tracking Epic: MeganovaAI/mega-nova-api#447

[flyworker]

Implemented in PR #15