fix(agent): add canvas_type filter and field to list_agents API (#15754)

### What problem does this PR solve?

GET /api/v1/agents (list_agents) already supports filtering by
canvas_category, keywords, tags, and owner_ids, but it does not support
canvas_type — even though canvas_type is a persisted field on UserCanvas
and is already accepted on agent create/update APIs.

This gap causes two issues:

Filtering — clients cannot list agents by business category (e.g.
Marketing, Agent, Ingestion Pipeline) without fetching all agents and
filtering client-side.
Response payload — list_agents did not return canvas_type in each canvas
item, so consumers had to call GET /api/v1/agents/{id} per agent to read
it.
This PR adds optional canvas_type query parameter support and includes
canvas_type in the list response.
### Type of change

- [√] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

api/apps/restful_apis/agent_api.py

@@ -641,6 +641,7 @@ def prompts():
 def list_agents(tenant_id):
     keywords = request.args.get("keywords", "")
     canvas_category = request.args.get("canvas_category")
+    canvas_type = request.args.get("canvas_type")
     owner_ids = [item for item in request.args.get("owner_ids", "").strip().split(",") if item]
     tags = [item for item in request.args.get("tags", "").strip().split(",") if item]
 
@@ -675,6 +676,7 @@ def list_agents(tenant_id):
         keywords,
         canvas_category,
         tags,
+        canvas_type,
     )
 
     return get_json_result(data={"canvas": canvas, "total": total})

api/db/services/canvas_service.py

@@ -152,6 +152,7 @@ class UserCanvasService(CommonService):
         keywords,
         canvas_category=None,
         tags=None,
+        canvas_type=None,
     ):
         fields = [
             cls.model.id,
@@ -163,6 +164,7 @@ class UserCanvasService(CommonService):
             User.nickname,
             User.avatar.alias('tenant_avatar'),
             cls.model.update_time,
+            cls.model.canvas_type,
             cls.model.canvas_category,
             cls.model.tags,
         ]
@@ -177,6 +179,8 @@ class UserCanvasService(CommonService):
             )
         if canvas_category:
             agents = agents.where(cls.model.canvas_category == canvas_category)
+        if canvas_type:
+            agents = agents.where(cls.model.canvas_type == canvas_type)
         if tags:
             tag_list = [t.strip() for t in tags if t and t.strip()] if isinstance(tags, (list, tuple)) else [t.strip() for t in str(tags).split(",") if t.strip()]
             if tag_list: