feat: add Novita AI as a built-in LLM provider

[Alex-wuhu]

Summary

Adds Novita AI as a first-class provider alongside Anthropic, OpenAI, and OpenCode.

Novita exposes an OpenAI-compatible API, so this integration reuses the existing codex harness with a custom OPENAI_BASE_URL. No new CLI dependency is required.

Supported models (from Novita's catalog):

Model ID	Notes
moonshotai/kimi-k2.5	Default — 262k context, function calling, vision
zai-org/glm-5	202k context, function calling
minimax/minimax-m2.5	204k context, function calling

Configuration

// ~/.tinyagi/settings.json
{
  "models": {
    "provider": "novita",
    "novita": {
      "model": "moonshotai/kimi-k2.5",
      "auth_token": "<NOVITA_API_KEY>"
    }
  }
}

Or set the NOVITA_API_KEY environment variable — the provider picks it up automatically.

CLI

tinyagi provider novita --model moonshotai/kimi-k2.5 --auth-token <key>

Changes

• packages/core/src/types.ts — add novita to Settings.models; add model aliases to MODEL_ALIASES
• packages/core/src/config.ts — auto-detect novita from settings; default model in getDefaultAgentFromModels
• packages/core/src/invoke.ts — inject OPENAI_API_KEY + OPENAI_BASE_URL for novita, route through codex harness
• packages/cli/src/shared.ts — add novita to providerOptions(), add novitaModelOptions(), wire into promptModel()
• packages/cli/src/provider.ts — accept novita in CLI dispatch; provider-appropriate hints; generic modelSection lookup