fix: escape backslashes in mock tool call argument paths for Windows

The OpenAI and OpenAI Chat mocks were sending file paths without proper
JSON escaping. On Windows, paths contain backslashes that need to be
escaped as \\\\ in JSON strings.

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca <[email protected]>

Author: ArthurHeymans

integration-test/llm_mock/openai.clj

@@ -152,7 +152,7 @@
         (sse-send! ch "response.function_call_arguments.delta"
                    {:type "response.function_call_arguments.delta"
                     :item_id "item-1"
-                    :delta (str "h\":\"" (h/project-path->canon-path "resources") "\"}")})
+                    :delta (str "h\":\"" (h/json-escape-path (h/project-path->canon-path "resources")) "\"}")})
         ;; Complete with the function call present so the client triggers tools
         (sse-send! ch "response.completed"
                    {:type "response.completed"

integration-test/llm_mock/openai_chat.clj

@@ -114,7 +114,7 @@
   (send-sse! ch {:choices [{:delta {:tool_calls [{:index 0
                                                    :function {:arguments "{\"pat"}}]}}]})
   (send-sse! ch {:choices [{:delta {:tool_calls [{:index 0
-                                                   :function {:arguments (str "h\":\"" path "\"}")}}]}}]})
+                                                   :function {:arguments (str "h\":\"" (h/json-escape-path path) "\"}")}}]}}]})
   (send-sse! ch {:usage {:prompt_tokens 5 :completion_tokens 30}})
   (send-sse! ch {:choices [{:delta {} :finish_reason "tool_calls"}]})
   (hk/close ch))