add tts api (#2107)

### What problem does this PR solve?

add tts api 


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

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

api/apps/conversation_app.py

 #
 from copy import deepcopy
 from flask import request, Response
-from flask_login import login_required
+from flask_login import login_required,current_user
 from api.db.services.dialog_service import DialogService, ConversationService, chat
+from api.db.services.llm_service import LLMBundle, TenantService
+from api.db import LLMType
 from api.utils.api_utils import server_error_response, get_data_error_result, validate_request
 from api.utils import get_uuid
 from api.utils.api_utils import get_json_result
         return server_error_response(e)
 
 
+@manager.route('/tts', methods=['POST'])
+@login_required
+def tts():
+    req = request.json
+    text = req["text"]
+    
+    tenants = TenantService.get_by_user_id(current_user.id)
+    if not tenants:
+        return get_data_error_result(retmsg="Tenant not found!")
+    
+    tts_id = tenants[0]["tts_id"]
+    if not tts_id:
+        return get_data_error_result(retmsg="No default TTS model is set")
+    
+    tts_mdl = LLMBundle(tenants[0]["tenant_id"], LLMType.TTS, tts_id)
+    def stream_audio():
+        try:
+            for chunk in tts_mdl(text):  
+                yield chunk  
+        except Exception as e:
+            yield "data:" + json.dumps({"retcode": 500, "retmsg": str(e),
+                            "data": {"answer": "**ERROR**: "+str(e)}},
+                            ensure_ascii=False).encode('utf-8')
+
+    resp = Response(stream_audio(), mimetype="audio/mpeg")  
+    resp.headers.add_header("Cache-Control", "no-cache")
+    resp.headers.add_header("Connection", "keep-alive")
+    resp.headers.add_header("X-Accel-Buffering", "no")
+    
+    return resp
+
+    
 @manager.route('/delete_msg', methods=['POST'])
 @login_required
 @validate_request("conversation_id", "message_id")
             break
 
     ConversationService.update_by_id(conv["id"], conv)
-    return get_json_result(data=conv)
+    return get_json_result(data=conv)

api/db/services/user_service.py

             cls.model.rerank_id,
             cls.model.asr_id,
             cls.model.img2txt_id,
+            cls.model.tts_id,
             cls.model.parser_ids,
             UserTenant.role]
         return list(cls.model.select(*fields)