feat: enhance condition node functionality with branches and validation

- Introduced WorkflowConditionBranch and WorkflowNodeConfig types to manage condition branches in nodes.
- Updated NodeConfigPanel and ConditionNodePanel components to support adding, editing, and deleting branches.
- Implemented validation for condition nodes to ensure at least one branch exists and that default branches are correctly configured.
- Modified workflow-utils to handle condition branches and updated toApiDefinition and fromApiDefinition functions to maintain branch integrity during serialization.
- Removed edge condition handling from WorkflowEditor and related components, simplifying edge management.
- Added tests to ensure condition branches are preserved in API definitions.

internal/ai/workflow/dsl/types.go

@@ -24,10 +24,21 @@ type Position struct {
 }
 
 type Edge struct {
-	ID        string     `json:"id"`
-	Source    string     `json:"source"`
-	Target    string     `json:"target"`
-	Condition *Condition `json:"condition,omitempty"`
+	ID     string `json:"id"`
+	Source string `json:"source"`
+	Target string `json:"target"`
+}
+
+type ConditionConfig struct {
+	Branches []ConditionBranch `json:"branches,omitempty"`
+}
+
+type ConditionBranch struct {
+	ID           string     `json:"id"`
+	Name         string     `json:"name,omitempty"`
+	TargetNodeID string     `json:"targetNodeId"`
+	Condition    *Condition `json:"condition,omitempty"`
+	Default      bool       `json:"default,omitempty"`
 }
 
 type Condition struct {