fix: ranking refresh deadlock, switch to direct HTTP, add CI pipeline

- Fix channel drain goroutine deadlock in handleRankingRefresh: replace
  'for { ... continue ... if nil break }' with 'for A != nil || B != nil'
  so the select never blocks on two nil channels
- Switch ScrapeRanking from urlClient (Browserless) to client (direct HTTP)
  since novelfire.net/ranking is fully server-rendered — no JS needed
- Add ranking unit tests (single page, multi-page, empty page, write round-trip)
- Add .gitea/workflows/ci.yaml: lint, test, build jobs with commented-out
  Docker image push step for when runner has Docker available

scraper/internal/server/ui.go

@@ -455,35 +455,30 @@ func (s *Server) handleRankingRefresh(w http.ResponseWriter, r *http.Request) {
 		rankingCh, errCh := s.novel.ScrapeRanking(ctx, maxPages)
 
 		var rankingItems []writer.RankingItem
-		for {
+		for rankingCh != nil || errCh != nil {
 			select {
 			case meta, ok := <-rankingCh:
 				if !ok {
 					rankingCh = nil
-					continue
+				} else {
+					rankingItems = append(rankingItems, writer.RankingItem{
+						Rank:      meta.Ranking,
+						Slug:      meta.Slug,
+						Title:     meta.Title,
+						Author:    meta.Author,
+						Cover:     meta.Cover,
+						Status:    meta.Status,
+						Genres:    meta.Genres,
+						SourceURL: meta.SourceURL,
+					})
 				}
-				rankingItems = append(rankingItems, writer.RankingItem{
-					Rank:      meta.Ranking,
-					Slug:      meta.Slug,
-					Title:     meta.Title,
-					Author:    meta.Author,
-					Cover:     meta.Cover,
-					Status:    meta.Status,
-					Genres:    meta.Genres,
-					SourceURL: meta.SourceURL,
-				})
 			case err, ok := <-errCh:
 				if !ok {
 					errCh = nil
-					continue
-				}
-				if err != nil {
+				} else if err != nil {
 					s.log.Error("ranking scrape error", "err", err)
 				}
 			}
-			if rankingCh == nil && errCh == nil {
-				break
-			}
 		}
 
 		if len(rankingItems) > 0 {