fix(shell,config): terminal font size, AI tools, provider keys

- Fix terminal default fontSize from 6px to 14px across all references
- Add terminal tool to shell AI via ChatEngine with tool_call streaming
- Fix provider key detection (apiKey → api_key, baseURL → base_url)
- Add mimo provider migration and validation endpoint
- Bump version to 0.4.0

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

internal/api/handlers_config.go

@@ -187,6 +187,8 @@ func (s *Server) handleValidateProvider(w http.ResponseWriter, r *http.Request)
 		switch body.Name {
 		case "minimax":
 			baseURL = "https://api.minimax.io/v1"
+		case "mimo":
+			baseURL = "https://token-plan-ams.xiaomimimo.com/v1"
 		case "openai":
 			baseURL = "https://api.openai.com/v1"
 		case "anthropic":