fix(saas): deep audit round industry template system - critical fixes

C1: Use backend createAgentFromTemplate API + tools forwarding
C3: seed source='builtin' instead of 'custom'
C4: immutable clone data handling (return fresh from store) + spread)
H3: assignTemplate error propagation (try/catch)
H4: input validation for name/fields
H5: assign_template account existence check
H6: remove dead route get_full_template
H7: model fallback gpt-4o-mini (hardcoded constant)
H8: logout clears template state
H9: console.warn -> structured logger
C2: restoreSession fetches assignedTemplate

crates/zclaw-saas/src/agent_template/service.rs

@@ -368,7 +368,8 @@ pub async fn create_agent_from_template(
 
     Ok(AgentConfigFromTemplate {
         name: t.name,
-        model: t.model.unwrap_or_else(|| "glm-4-flash".to_string()),
+        model: t.model.unwrap_or_else(|| "gpt-4o-mini".to_string()),
+
         system_prompt: t.system_prompt,
         tools: merged_tools,
         soul_content: t.soul_content,