add Gemini 3.1 preview model support to OpenRouter catalog

[TypQxQ]

What does this PR do?

This PR adds support for the Gemini 3.1 preview models (google/gemini-3.1-pro-preview and google/gemini-3.1-flash-lite-preview) to the static OpenRouter model catalog, ensuring these models appear correctly in hermes setup and provider configuration menus.

Related Issue

Fixes #3753

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• Added Gemini 3.1 preview models to OPENROUTER_MODELS list.
• Preserved all existing Gemini 3.0-preview models to maintain backward compatibility.

How to Test

1. Run hermes setup or explicitly invoke the model selector in a chat using /model openrouter.
2. Verify that both the legacy google/gemini-3-pro-preview and the new google/gemini-3.1-pro-preview (along with their Flash counterparts) appear in the selection menu.

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: Ubuntu 24.04

Documentation & Housekeeping

• [N/A] I've updated relevant documentation (README, docs/, docstrings) — or N/A
• [N/A] I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• [N/A] I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• [N/A] I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• [N/A] I've updated tool descriptions/schemas if I changed tool behavior — or N/A

[teknium1]

Merged via PR #3803 with completeness fix. Your commit adding Gemini 3.1 models to OPENROUTER_MODELS was cherry-picked with authorship preserved — also added the same models to the nous provider list which was missing. Thanks @TypQxQ!