chore: remove iFlow-related modules and dependencies

- Deleted `iflow` provider implementation, including thinking configuration (`apply.go`) and authentication modules.
- Removed iFlow-specific tests, executors, and helpers across SDK and internal components.
- Updated all references to exclude iFlow functionality.

sdk/cliproxy/service.go

@@ -392,7 +392,7 @@ func (s *Service) ensureExecutorsForAuthWithMode(a *coreauth.Auth, forceReplace
 	}
 	// Skip disabled auth entries when (re)binding executors.
 	// Disabled auths can linger during config reloads (e.g., removed OpenAI-compat entries)
-	// and must not override active provider executors (such as iFlow OAuth accounts).
+	// and must not override active provider executors.
 	if a.Disabled {
 		return
 	}
@@ -422,8 +422,6 @@ func (s *Service) ensureExecutorsForAuthWithMode(a *coreauth.Auth, forceReplace
 		s.coreManager.RegisterExecutor(executor.NewAntigravityExecutor(s.cfg))
 	case "claude":
 		s.coreManager.RegisterExecutor(executor.NewClaudeExecutor(s.cfg))
-	case "iflow":
-		s.coreManager.RegisterExecutor(executor.NewIFlowExecutor(s.cfg))
 	case "kimi":
 		s.coreManager.RegisterExecutor(executor.NewKimiExecutor(s.cfg))
 	default:
@@ -926,9 +924,6 @@ func (s *Service) registerModelsForAuth(a *coreauth.Auth) {
 			}
 		}
 		models = applyExcludedModels(models, excluded)
-	case "iflow":
-		models = registry.GetIFlowModels()
-		models = applyExcludedModels(models, excluded)
 	case "kimi":
 		models = registry.GetKimiModels()
 		models = applyExcludedModels(models, excluded)