fix(web): add missing query parameter to autocomplete API URL

The OpenAlex autocomplete API URL was malformed with `?=` instead of `?q=`,
causing the autocomplete dropdown to never show suggestions. This fix adds
the required `q` query parameter name.

Before: https://api.openalex.org/autocomplete?=${query}
After: https://api.openalex.org/autocomplete?q=${query}

Author: Mearman

apps/web/src/components/layout/HeaderSearchInput.tsx

@@ -126,7 +126,7 @@ export const HeaderSearchInput = () => {
 
       // OpenAlex API for autocomplete suggestions
       const response = await fetch(
-        `https://api.openalex.org/autocomplete?=${encodeURIComponent(searchQuery)}`,
+        `https://api.openalex.org/autocomplete?q=${encodeURIComponent(searchQuery)}`,
         {
           signal: abortController.signal,
           headers: {