fix(cli): add google/ publisher prefix normalization for Vertex AI

[hashbender]

What does this PR do?

Adds a dedicated normalization handler for the vertex provider in normalize_model_for_provider(). Vertex AI endpoints require model IDs in the google/MODEL_NAME format (e.g. google/gemini-3.1-flash-lite), but bare names like gemini-3.1-flash-lite were passed through unchanged, causing HTTP 400 INVALID_ARGUMENT errors from the Vertex API.

Related Issue

Fixes NousResearch#56778

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• hermes_cli/model_normalize.py: Added a vertex provider block that prepends google/ to bare model names, preserves names already carrying the google/ prefix, and strips a matching vertex/ prefix before adding google/. Added two docstring examples.
• tests/hermes_cli/test_vertex_provider.py: Added TestVertexModelNormalization class with 4 test methods covering bare names, already-prefixed names, vertex/ prefix stripping, and empty input.

How to Test

1. Run the new normalization tests:

   python -m pytest tests/hermes_cli/test_vertex_provider.py -q -k "TestVertexModelNormalization"

   All 7 parametrized cases should pass.

2. Run the full vertex provider test suite to check for regressions:

   python -m pytest tests/hermes_cli/test_vertex_provider.py -q

   All 29 tests should pass.

3. Verify normalization behavior interactively:

   from hermes_cli.model_normalize import normalize_model_for_provider
   assert normalize_model_for_provider("gemini-3.1-flash-lite", "vertex") == "google/gemini-3.1-flash-lite"
   assert normalize_model_for_provider("google/gemini-2.5-pro", "vertex") == "google/gemini-2.5-pro"

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: macOS (Python 3.12)

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — docstring examples added
• I've updated cli-config.yaml.example if I added/changed config keys — N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — pure string normalization, no platform-specific code
• I've updated tool descriptions/schemas if I changed tool behavior — N/A

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Mirror-of: NousResearch#56805
NousResearch#56805