Price current Claude 5 and Gemini 3.6 model families

[mostlydev]

Motivation

cllama budget enforcement treats an unpriced model as zero cost. Current provider aliases now include claude-fable-5, claude-opus-5, claude-sonnet-5, and gemini-3.6-flash, but the built-in pricing table stops at Claude 4.6 / Haiku 4.5 and Gemini 2.5. Runnable downstream examples therefore cannot safely adopt the current aliases without weakening budget enforcement.

Current official prices

• Claude Fable 5: USD 10 input / 50 output per million tokens.
• Claude Opus 5: USD 5 input / 25 output per million tokens.
• Claude Sonnet 5: standard USD 3 input / 15 output per million tokens. Anthropic promotional pricing is USD 2 / 10 through 2026-08-31; use the standard ceiling in the static table so enforcement does not become stale or undercount after the promotion.
• Claude Haiku 4.5: USD 1 input / 5 output per million tokens; correct the current 0.8 / 4 row.
• Gemini 3.6 Flash: USD 1.50 input / 7.50 output per million tokens.

Official sources:

• https://platform.claude.com/docs/en/about-claude/models/overview
• https://platform.claude.com/docs/en/about-claude/pricing
• https://ai.google.dev/gemini-api/docs/pricing
• https://ai.google.dev/gemini-api/docs/models/gemini-3.6-flash

Scope

• Add exact Anthropic rows for the three Claude 5 public aliases.
• Correct Claude Haiku 4.5 pricing.
• Add direct Google pricing for gemini-3.6-flash.
• Add matching OpenRouter pass-through rows for the same public aliases.
• Add lookup and cost-computation tests, including date-suffixed/prefix compatibility where the provider publishes such shapes.
• Preserve older model rows for broad compatibility.

Acceptance

• go test ./... and go vet ./... pass.
• Current aliases never fall through to zero-cost accounting.
• The static table uses conservative standard Sonnet 5 pricing across the 2026-08-31 promotion boundary.
• Land before the v0.9.0 tag so downstream runnable examples can move to current aliases in the release that pins v0.9.0.