Default browser_vision screenshots to google/gemma-4-27b-it (Gemma 4
native multimodal) for reduced latency and unified text+vision model.
Resolution order for _get_vision_model():
1. BROWSER_VISION_MODEL env var (new, browser-specific override)
2. auxiliary.browser_vision.model in config.yaml (new config key)
3. AUXILIARY_VISION_MODEL env var (existing global vision override)
4. Default: google/gemma-4-27b-it
Backward compatibility: existing AUXILIARY_VISION_MODEL users are
unaffected — their override still flows through to browser_vision.
Also documents the new auxiliary.browser_vision config section in
cli-config.yaml.example and adds 14 unit tests covering the full
priority chain.
Fixes#816
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
95bb842a21