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
