feat: add NovitaAI as LLM provider

Add NovitaAI as a first-class provider with dedicated model selection
flow, live pricing, and authoritative context length resolution.

- Register provider in PROVIDER_REGISTRY, HERMES_OVERLAYS, and all
  alias/label maps (ID: novita, aliases: novita-ai, novitaai)
- Add dedicated _model_flow_novita() with 3-tier model list fallback:
  Novita API → models.dev → static curated list
- Fetch live pricing from /v1/models with correct unit conversion
  (input_token_price_per_m is 0.0001 USD per Mtok)
- Add Novita-specific context length resolution (step 4b) in
  get_model_context_length(), prioritized over models.dev/OpenRouter
- Register api.novita.ai in _URL_TO_PROVIDER to prevent early return
  from the custom-endpoint code path
- Add models.dev mapping (novita → novita-ai)
- Add default auxiliary model (deepseek/deepseek-v3-0324)
- Add NOVITA_API_KEY to test isolation (conftest.py)
- Update docs: providers page, env vars reference, CLI reference,
  .env.example, README, and landing page

website/docs/integrations/providers.md

@@ -20,6 +20,7 @@ You need at least one way to connect to an LLM. Use `hermes model` to switch pro
 | **GitHub Copilot ACP** | `hermes model` (spawns local `copilot --acp --stdio`) |
 | **Anthropic** | `hermes model` (Claude Max + extra usage credits via OAuth; also supports Anthropic API key or manual setup-token — see note below) |
 | **OpenRouter** | `OPENROUTER_API_KEY` in `~/.hermes/.env` |
+| **NovitaAI** | `NOVITA_API_KEY` in `~/.hermes/.env` (provider: `novita`, multi-model aggregator) |
 | **AI Gateway** | `AI_GATEWAY_API_KEY` in `~/.hermes/.env` (provider: `ai-gateway`) |
 | **z.ai / GLM** | `GLM_API_KEY` in `~/.hermes/.env` (provider: `zai`) |
 | **Kimi / Moonshot** | `KIMI_API_KEY` in `~/.hermes/.env` (provider: `kimi-coding`) |
@@ -546,6 +547,29 @@ You can append routing suffixes to model names: `:fastest` (default), `:cheapest
 
 The base URL can be overridden with `HF_BASE_URL`.
 
+### NovitaAI
+
+[NovitaAI](https://novita.ai) is a multi-model aggregator with pay-per-use pricing. Access models from DeepSeek, Kimi, MiniMax, GLM, Qwen, and more through a unified OpenAI-compatible API.
+
+```bash
+# Use any available model
+hermes chat --provider novita --model moonshotai/kimi-k2.5
+# Requires: NOVITA_API_KEY in ~/.hermes/.env
+
+# Short alias
+hermes chat --provider novita-ai --model deepseek/deepseek-v3-0324
+```
+
+Or set it permanently in `config.yaml`:
+```yaml
+model:
+  provider: "novita"
+  default: "moonshotai/kimi-k2.5"
+  base_url: "https://api.novita.ai/openai/v1"
+```
+
+Get your API key at [novita.ai/settings/key-management](https://novita.ai/settings/key-management). The base URL can be overridden with `NOVITA_BASE_URL`.
+
 ## Custom & Self-Hosted LLM Providers
 
 Hermes Agent works with **any OpenAI-compatible API endpoint**. If a server implements `/v1/chat/completions`, you can point Hermes at it. This means you can use local models, GPU inference servers, multi-provider routers, or any third-party API.