feat: use Google Gemini as default vision backend, make provider configurable

- Plugin options: baseURL, apiKey, model, providerID, visionModels
- Default: Google Gemini OpenAI-compatible endpoint, gemini-2.5-flash
- Support {env:VAR} templates and GEMINI_API_KEY fallback
- Legacy fallback to ludmila-ai provider block for existing setups
- vision.md subagent now uses google/gemini-2.5-flash

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vision-bridge",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "type": "module",
   "description": "Opencode plugin: bridges images to a vision model when the active model cannot see images.",
   "main": "src/vision-bridge.ts",