server: support Vertex AI compatible API (#22545)

* server: support Vertex AI compatible API

* a bit safer

* support other AIP_* env var

* various fixes

* if AIP_MODE is unset, do nothing

* fix test case

* fix windows build

tools/server/server.cpp

@@ -204,6 +204,10 @@ int main(int argc, char ** argv) {
     // Save & load slots
     ctx_http.get ("/slots",                    ex_wrapper(routes.get_slots));
     ctx_http.post("/slots/:id_slot",           ex_wrapper(routes.post_slots));
+
+    // Google Cloud Platform (Vertex AI) compat
+    ctx_http.register_gcp_compat();
+
     // CORS proxy (EXPERIMENTAL, only used by the Web UI for MCP)
     if (params.webui_mcp_proxy) {
         SRV_WRN("%s", "-----------------\n");