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* fixup(llm): replace superseded DeepSeek Flash id with current Pro flagship

QA flagged that deepseek/deepseek-v4-flash-0731 has been superseded in the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>

README.md

@@ -75,8 +75,16 @@ Prefer to bring a key? Set one and skip the connect step:
 ```bash
 export OPENROUTER_API_KEY=...     # or VENICE_API_KEY / ANTHROPIC_API_KEY / OPENAI_API_KEY
 export XAI_API_KEY=...            # Grok Build (grok-build-0.1) — xAI's coding model, native tool-calling
+export NOVITA_API_KEY=...         # Novita AI's hosted OpenAI-compatible API
 ```
 
+Novita AI is an opt-in third-party hosted provider. Requests send the selected
+model id, prompts/context, generated output, and request metadata to Novita;
+your API key authenticates those requests. Review Novita's current
+[privacy policy](https://novita.ai/legal/privacy-policy) and
+[terms](https://novita.ai/legal/terms-of-service) before using sensitive target
+data. T3MP3ST does not claim independent assurance for sensitive workloads.
+
 Slow local agents can be given more room with `T3MP3ST_LOCAL_AGENT_TIMEOUT_MS`
 for each CLI call, `T3MP3ST_TASK_TIMEOUT_MS` for mission tasks, and
 `T3MP3ST_GENERAL_TIMEOUT_MS` for planning requests. Values are milliseconds.