Feat: Redesign and refactor agent module (#9113)

### What problem does this PR solve?

#9082 #6365

<u> **WARNING: it's not compatible with the older version of `Agent`
module, which means that `Agent` from older versions can not work
anymore.**</u>

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/db/init_data.py

@@ -154,6 +154,11 @@ def init_llm_factory():
 
 def add_graph_templates():
     dir = os.path.join(get_project_base_directory(), "agent", "templates")
+    CanvasTemplateService.filter_delete([1 == 1])
+    if not os.path.exists(dir):
+        logging.warning("Missing agent templates!")
+        return
+
     for fnm in os.listdir(dir):
         try:
             cnvs = json.load(open(os.path.join(dir, fnm), "r",encoding="utf-8"))
@@ -162,7 +167,7 @@ def add_graph_templates():
             except Exception:
                 CanvasTemplateService.update_by_id(cnvs["id"], cnvs)
         except Exception:
-            logging.exception("Add graph templates error: ")
+            logging.exception("Add agent templates error: ")
 
 
 def init_web_data():