fix(translate): Kilo API response_format, reasoning_effort skip, structured_outputs fallback, refusal handling

- Enable response_format (json_object) for all providers including Kilo/OpenRouter
- Skip reasoning_effort for Kilo/OpenRouter (returns 400 — mandatory reasoning)
- Add structured_outputs fallback: retry once without response_format if upstream
  provider (e.g. StepFun) rejects it with 'structured_outputs is not supported'
- Handle model refusal field (refusal) instead of treating as empty content
- Fix None-handling guards for message/finish_reason/content fields
- Apply same fixes to both preview.py and executor.py _call_openai_compatible
- Connect orphaned TermCorrectionPopup, BulkReplaceModal, BulkCorrectionSidebar

frontend/src/lib/api/translate.js

@@ -646,7 +646,16 @@ export async function bulkReplacePreview(runId, data) {
 // @PURPOSE: Download skipped records CSV for a run.
 export async function downloadSkippedCsv(runId) {
 	try {
-		return await api.fetchApi(`/translate/runs/${runId}/skipped.csv`);
+		const blob = await api.fetchApiBlob(`/translate/runs/${runId}/skipped.csv`);
+		// Trigger browser download
+		const url = URL.createObjectURL(blob);
+		const a = document.createElement('a');
+		a.href = url;
+		a.download = `skipped-${runId.substring(0, 8)}.csv`;
+		document.body.appendChild(a);
+		a.click();
+		document.body.removeChild(a);
+		URL.revokeObjectURL(url);
 	} catch (error) {
 		throw normalizeTranslateError(error, 'Failed to download skipped CSV');
 	}