Add Arcee provider pricing

[Kludex]

Closes #569.

Replaces #570.

Summary

• add the six models in the public Arcee Text Models pricing table
• support explicit provider IDs, the Arcee API URL, and OpenAI-compatible default and chat usage extraction
• add a deterministic public pricing updater with a committed cassette and offline replay test
• add agentic price monitoring and Python/JavaScript parity coverage
• avoid claiming third-party model namespaces without an Arcee provider ID or API URL

The authenticated-only seventh model and undocumented context windows from the replaced PR are intentionally excluded.

Verification

• make all
• uv run pytest tests/test_source_arcee.py --record-mode=none
• gh aw compile agentic-price-check-direct-providers --no-check-update --no-emit --validate --actionlint
• git diff --check

AI Disclaimer

This PR was developed with the assistance of either Claude or Codex. I have reviewed and verified the changes.

[cubic-dev-ai]

No issues found across 21 files

_{Re-trigger cubic}