use a fresh spooldb session per image instead of a shared one

server.go

@@ -15,9 +15,10 @@ import (
 //go:embed index.html
 var indexHTML []byte
 
-// serve runs the mobile putaway web server. Requests are serialized because the
-// shared spooldb browser session is single-threaded.
-func serve(addr string, auth claude.Auth, sp *spoolSync, dryRun bool) error {
+// serve runs the mobile putaway web server. Each request gets its own fresh
+// spooldb session; requests are serialized so we never run several headless
+// browsers at once.
+func serve(addr string, auth claude.Auth, dryRun bool) error {
 	var mu sync.Mutex
 
 	mux := http.NewServeMux()
@@ -53,7 +54,7 @@ func serve(addr string, auth claude.Auth, sp *spoolSync, dryRun bool) error {
 
 		start := time.Now()
 		mu.Lock()
-		res := processImg(img, hdr.Filename, auth, sp, dryRun)
+		res := processImg(img, hdr.Filename, auth, dryRun)
 		mu.Unlock()
 		slog.Info("processed upload", "file", hdr.Filename, "spool", res.SpoolID, "dur", time.Since(start))