Preserve per-source pacing across queue jobs and add source pause

scraper/jobs/mangadex-archive.js

@@ -69,7 +69,7 @@ async function runMangaDexArchive(options) {
   const chapterMinMs = Number(options.chapterMinMs);
   const chapterMaxMs = Number(options.chapterMaxMs);
   const http = new SlowHttp({
-    minMs, maxMs, maxRetries: 2,
+    gateKey: 'mangadex', minMs, maxMs, maxRetries: 2,
     userAgent: 'MangaCircus-Scraper/1.0 (personal archival; sequential MangaDex requests)',
     onEvent: item => event(item.level, item.message, { status: item.status }),
   });