fix(cli): split path and query in buildUrl to prevent %3F encoding

The URL constructor's pathname setter encodes ? as %3F, breaking
heartbeat event polling. Split query params before assignment.

Fixes #204

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cli/src/client/http.ts

@@ -104,8 +104,10 @@ export class PaperclipApiClient {
 
 function buildUrl(apiBase: string, path: string): string {
   const normalizedPath = path.startsWith("/") ? path : `/${path}`;
+  const [pathname, query] = normalizedPath.split("?");
   const url = new URL(apiBase);
-  url.pathname = `${url.pathname.replace(/\/+$/, "")}${normalizedPath}`;
+  url.pathname = `${url.pathname.replace(/\/+$/, "")}${pathname}`;
+  if (query) url.search = query;
   return url.toString();
 }