feat: add service name to app-server (#12319)

Add service name to the app-server so that the app can use it's own
service name

This is on thread level because later we might plan the app-server to
become a singleton on the computer

codex-rs/app-server-protocol/schema/json/ClientRequest.json

@@ -2190,6 +2190,12 @@
               "type": "null"
             }
           ]
+        },
+        "serviceName": {
+          "type": [
+            "string",
+            "null"
+          ]
         }
       },
       "type": "object"

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -13323,6 +13323,12 @@
                 "type": "null"
               }
             ]
+          },
+          "serviceName": {
+            "type": [
+              "string",
+              "null"
+            ]
           }
         },
         "title": "ThreadStartParams",

codex-rs/app-server-protocol/schema/json/v2/ThreadStartParams.json

@@ -150,6 +150,12 @@
           "type": "null"
         }
       ]
+    },
+    "serviceName": {
+      "type": [
+        "string",
+        "null"
+      ]
     }
   },
   "title": "ThreadStartParams",