feat(llm): add native Novita AI provider via OpenAI-compatible endpoint (#155)

* feat(llm): add native Novita AI provider via OpenAI-compatible endpoint

Wire Novita AI (https://api.novita.ai/openai/v1) as a first-class LLM
provider, following the same pattern used for DeepSeek/HuggingFace/NanoGPT:
dispatched through the existing OpenAIAdapter, resolved via NOVITA_API_KEY,
with a default model, model catalog entries, config/setup wiring, and
regression tests.

* fixup(llm): use deepseek/deepseek-v4-flash-0731 as the second Novita model

Swap the curated Novita model catalog's second entry from
qwen/qwen3-coder-30b-a3b-instruct to deepseek/deepseek-v4-flash-0731 per
requested model selection. Verified live against api.novita.ai/openai/v1/models.

* fixup(llm): replace superseded DeepSeek Flash id with current Pro flagship

QA flagged that deepseek/deepseek-v4-flash-0731 has been superseded in the
live Novita catalog; deepseek/deepseek-v4-pro-0813 is now the current
serving DeepSeek flagship. Swap the second Novita model catalog entry
accordingly.

---------

Co-authored-by: jax-novita <jax-novita@users.noreply.github.com>
Co-authored-by: Joseph Magly <1159087+jmagly@users.noreply.github.com>

docsite/t3mp3st-docs/content/GETTING_STARTED.md

@@ -55,10 +55,17 @@ export VENICE_API_KEY=...
 export ANTHROPIC_API_KEY=...
 export OPENAI_API_KEY=...
 export DEEPSEEK_API_KEY=...
+export NOVITA_API_KEY=...         # third-party hosted OpenAI-compatible API
 export LITELLM_BASE_URL=http://localhost:4000/v1
 export LITELLM_API_KEY=...        # only if your LiteLLM proxy requires one
 ```
 
+Hosted providers receive the model id, prompts/context, generated output, and
+request metadata needed to serve the request. For Novita, review the current
+[privacy policy](https://novita.ai/legal/privacy-policy) and
+[terms](https://novita.ai/legal/terms-of-service) before sending sensitive
+target data; T3MP3ST does not independently certify it for sensitive workloads.
+
 Local/offline example with Ollama:
 
 ```bash