Move scrape form to dedicated /scrape page, add '+ Add' link in home header

- Extract scrape form and autocomplete JS from homeTmpl into new scrapeTmpl
- Add handleScrape GET handler serving /scrape with ranking autocomplete
- Register GET /scrape route in server.go
- Replace inline scrape form on home page with '+ Add' flat button in header
- handleHome no longer loads ranking items (only needed on /scrape)

scraper/internal/server/server.go

@@ -70,6 +70,7 @@ func (s *Server) ListenAndServe(ctx context.Context) error {
 	mux.HandleFunc("POST /scrape/book", s.handleScrapeBook)
 	// UI routes
 	mux.HandleFunc("GET /", s.handleHome)
+	mux.HandleFunc("GET /scrape", s.handleScrape)
 	mux.HandleFunc("GET /ranking", s.handleRanking)
 	mux.HandleFunc("POST /ranking/refresh", s.handleRankingRefresh)
 	mux.HandleFunc("GET /ranking/view", s.handleRankingView)