just declare the helper locally

Author: kvc0

tools/server/server-common.cpp

@@ -1433,6 +1433,8 @@ json convert_responses_to_chatcmpl(const json & response_body) {
     return chatcmpl_body;
 }
 
+// re-format an x-anthropic-billing-header system prompt's cch section for prompt caching friendliness
+void normalize_anthropic_billing_header(std::string & system_text);
 // Edits the cch section of an "x-anthropic-billing-header" system prompt.
 // Does nothing to any other prompt.
 //

tools/server/server-common.h

@@ -347,9 +347,6 @@ std::string format_oai_resp_sse(const json & data);
 // format Anthropic-style SSE with event types
 std::string format_anthropic_sse(const json & data);
 
-// re-format an x-anthropic-billing-header system prompt's cch section for prompt caching friendliness
-void normalize_anthropic_billing_header(std::string & system_text);
-
 bool is_valid_utf8(const std::string & str);
 
 //