fix(report): pass the in-app locale through to the pdf export

The health-record export panel sent no locale, so the server resolved the
report language from the browser's Accept-Language header. A German user on
an English-default browser got an English doctor report.

Send the active in-app locale from the panel, and on the server resolve
most-specific-first: explicit selection, then the healthlog-locale cookie
(what the user actually chose in the UI), then Accept-Language as the
weakest fallback.

src/components/settings/health-record-export-panel.tsx

@@ -97,7 +97,7 @@ function buildSelectionSections(s: SectionState) {
 }
 
 export function HealthRecordExportPanel() {
-  const { t } = useTranslations();
+  const { t, locale } = useTranslations();
   const [format, setFormat] = useState<ExportFormat>("pdf");
   const [days, setDays] = useState<number>(90);
   const [practiceName, setPracticeName] = useState("");
@@ -140,6 +140,10 @@ export function HealthRecordExportPanel() {
         credentials: "include",
         body: JSON.stringify({
           format,
+          // Carry the active in-app locale so the generated artefact matches
+          // the UI language instead of falling back to the browser's
+          // Accept-Language header on the server.
+          locale,
           range: { days },
           practiceName: practiceName.trim() || undefined,
           includeCharts,