fix(tasks): correct enum variant ordering for deserialization (#634)

Move CustomRequest and CustomResult to end of their respective untagged
enums to ensure specific task variants match before catch-all custom types.
Add deny_unknown_fields to GetTaskInfoResult to prevent matching arbitrary
JSON objects.

Fixes issue where tasks/get, tasks/list, tasks/result, and tasks/cancel
incorrectly deserialized as CustomRequest instead of their typed variants.

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -862,9 +862,6 @@
         {
           "$ref": "#/definitions/RequestOptionalParam4"
         },
-        {
-          "$ref": "#/definitions/CustomRequest"
-        },
         {
           "$ref": "#/definitions/Request9"
         },
@@ -876,6 +873,9 @@
         },
         {
           "$ref": "#/definitions/Request11"
+        },
+        {
+          "$ref": "#/definitions/CustomRequest"
         }
       ],
       "required": [

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema_current.json

@@ -862,9 +862,6 @@
         {
           "$ref": "#/definitions/RequestOptionalParam4"
         },
-        {
-          "$ref": "#/definitions/CustomRequest"
-        },
         {
           "$ref": "#/definitions/Request9"
         },
@@ -876,6 +873,9 @@
         },
         {
           "$ref": "#/definitions/Request11"
+        },
+        {
+          "$ref": "#/definitions/CustomRequest"
         }
       ],
       "required": [

crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema.json

@@ -857,7 +857,8 @@
             }
           ]
         }
-      }
+      },
+      "additionalProperties": false
     },
     "Icon": {
       "description": "A URL pointing to an icon resource or a base64-encoded data URI.\n\nClients that support rendering icons MUST support at least the following MIME types:\n- image/png - PNG images (safe, universal compatibility)\n- image/jpeg (and image/jpg) - JPEG images (safe, universal compatibility)\n\nClients that support rendering icons SHOULD also support:\n- image/svg+xml - SVG images (scalable but requires security precautions)\n- image/webp - WebP images (modern, efficient format)",
@@ -2452,9 +2453,6 @@
         {
           "$ref": "#/definitions/EmptyObject"
         },
-        {
-          "$ref": "#/definitions/CustomResult"
-        },
         {
           "$ref": "#/definitions/CreateTaskResult"
         },
@@ -2466,6 +2464,9 @@
         },
         {
           "$ref": "#/definitions/TaskResult"
+        },
+        {
+          "$ref": "#/definitions/CustomResult"
         }
       ]
     },

crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema_current.json

@@ -857,7 +857,8 @@
             }
           ]
         }
-      }
+      },
+      "additionalProperties": false
     },
     "Icon": {
       "description": "A URL pointing to an icon resource or a base64-encoded data URI.\n\nClients that support rendering icons MUST support at least the following MIME types:\n- image/png - PNG images (safe, universal compatibility)\n- image/jpeg (and image/jpg) - JPEG images (safe, universal compatibility)\n\nClients that support rendering icons SHOULD also support:\n- image/svg+xml - SVG images (scalable but requires security precautions)\n- image/webp - WebP images (modern, efficient format)",
@@ -2452,9 +2453,6 @@
         {
           "$ref": "#/definitions/EmptyObject"
         },
-        {
-          "$ref": "#/definitions/CustomResult"
-        },
         {
           "$ref": "#/definitions/CreateTaskResult"
         },
@@ -2466,6 +2464,9 @@
         },
         {
           "$ref": "#/definitions/TaskResult"
+        },
+        {
+          "$ref": "#/definitions/CustomResult"
         }
       ]
     },