feat(pricing): add Claude Sonnet 5 intro pricing entry

[brunz-me]

Problem

Claude Sonnet 5 (claude-sonnet-5, launched 2026-06-30) has no entry in the official-docs pricing snapshot in agent/usage_pricing.py. Any session using it gets cost_status: unknown and estimated_cost_usd: 0.0, silently hiding real spend from hermes insights and any downstream cost-sync tooling.

Fix

Adds a PricingEntry for ("anthropic", "claude-sonnet-5") using the published introductory rate: $2/$10 per MTok in/out (cache read/write scaled the same way as sibling entries), effective through the 2026-08-31 intro window per Anthropic's pricing page. Left a comment flagging the entry needs bumping to $3/$15 after the intro window closes.

Testing

python -m pytest tests/agent/test_usage_pricing.py -q — 15 passed.

Source: https://platform.claude.com/docs/en/about-claude/pricing

[teknium1]

Thanks for identifying the missing native Anthropic pricing route. Current main supports anthropic/claude-sonnet-5 in hermes_cli/models.py:46, while agent/usage_pricing.py:660-661 routes it to the official snapshot and agent/usage_pricing.py:717-738 cannot find an entry; estimate_usage_cost() consequently returns unknown at agent/usage_pricing.py:928-930. The proposed values match Anthropic's current introductory pricing.

Problems

• The diff changes only agent/usage_pricing.py; please add a regression test. tests/agent/test_usage_pricing.py:221-252 provides the existing pattern for a newly added pricing row.

Suggested changes

• Exercise the native provider="anthropic" route with nonzero input, output, cache-read, and cache-write usage, asserting an estimated non-null result.

Automated hermes-sweeper review.

[teknium1]

Merged via PR #67932 — your introductory-pricing commit was cherry-picked onto current main with your authorship preserved (rebase merge). Your entry (with the 2026-08-31 reversion note) was kept as the canonical Sonnet 5 pricing over a competing standard-rate entry. Thanks!

#67932