[Feat] Add Gemini 3.7 Flash support

[zoomote]

​Opened on behalf of @taltas. View the task or mention @roomote for follow-up asks.

What changed

• Added Gemini 3.7 Flash to the Google Gemini API and GCP Vertex AI model catalogs.
• Registered its 1M context window, 64K output limit, multimodal and prompt-cache support, and low, medium, and high reasoning levels.
• Applied Google's introductory token pricing, including the current $0.50 per million cached tokens per hour storage rate.
• Added focused catalog coverage for the supported reasoning levels and cache storage price across both providers.

Why this change was made

Google released Gemini 3.7 Flash as a generally available model for agentic coding and complex workflows. Zoo Code needs first-party catalog metadata that matches Google's supported request options and current pricing before users select it through Gemini or Vertex.

Impact

Users can select Gemini 3.7 Flash with either a Google Gemini API key or GCP Vertex AI credentials. Zoo Code now avoids offering the unsupported minimal reasoning level and reports the correct introductory cache storage price.

Related PRs

• Zoo-Code-Docs documentation update

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[zoomote]

The supplied review was correct. Google documents only low, medium, and high thinking levels for Gemini 3.7 Flash and lists the introductory cache storage rate as $0.50 per million tokens per hour through December 31, 2026.

Fixed both Gemini API and Vertex AI catalogs and added focused regression coverage in 768c79e1e. I also corrected the unsupported minimal claim in the paired documentation PR with b1feef3.

Zoo Code package lint, type-checking, focused tests, the full pnpm test suite (7,370 passed), and commit-hook lint/type-checking all passed. Documentation type-checking and production build also passed. View the task.