perf(convert): parallelize batch conversion across worker pool

Batch convert processed files strictly sequentially. Parsing/converting
is CPU-bound and stateless per file, so run it across a GOMAXPROCS-sized
worker pool; zip writing and progress updates stay serialized in
original file order.

internal/server/handlers.go

@@ -15,6 +15,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"sort"
 	"strconv"
 	"strings"
@@ -1423,40 +1424,79 @@ func (s *Server) runConvertJob(jobID, tempDir string, inputFiles []convertInputF
 	success := 0
 	totalProcess := len(inputFiles)
 
-	for i, in := range inputFiles {
+	type convertOutcome struct {
+		name string
+		data any
+		fail string
+	}
+
+	workers := runtime.GOMAXPROCS(0)
+	if workers > totalProcess {
+		workers = totalProcess
+	}
+	if workers < 1 {
+		workers = 1
+	}
+
+	jobs := make(chan int)
+	results := make([]convertOutcome, totalProcess)
+
+	var wg sync.WaitGroup
+	for w := 0; w < workers; w++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for i := range jobs {
+				in := inputFiles[i]
 				s.jobManager.AppendJobLog(jobID, fmt.Sprintf("Processing %s", in.Name))
+
 				payload, err := os.ReadFile(in.Path)
 				if err != nil {
-			failures = append(failures, fmt.Sprintf("%s: %v", in.Name, err))
+					results[i] = convertOutcome{name: in.Name, fail: fmt.Sprintf("%s: %v", in.Name, err)}
 					continue
 				}
 
 				result, _, _, err := s.analyzeUploadedFile(in.Name, in.MIMEType, payload)
 				if err != nil {
-			failures = append(failures, fmt.Sprintf("%s: %v", in.Name, err))
-			progress := ((i + 1) * 100) / totalProcess
-			s.jobManager.UpdateJobStatus(jobID, CollectStatusRunning, progress, "")
+					results[i] = convertOutcome{name: in.Name, fail: fmt.Sprintf("%s: %v", in.Name, err)}
 					continue
 				}
 				if result == nil || result.Hardware == nil {
-			failures = append(failures, fmt.Sprintf("%s: no hardware data", in.Name))
-			progress := ((i + 1) * 100) / totalProcess
-			s.jobManager.UpdateJobStatus(jobID, CollectStatusRunning, progress, "")
+					results[i] = convertOutcome{name: in.Name, fail: fmt.Sprintf("%s: no hardware data", in.Name)}
 					continue
 				}
 
 				reanimatorData, err := exporter.ConvertToReanimator(result)
 				if err != nil {
-			failures = append(failures, fmt.Sprintf("%s: %v", in.Name, err))
+					results[i] = convertOutcome{name: in.Name, fail: fmt.Sprintf("%s: %v", in.Name, err)}
+					continue
+				}
+
+				results[i] = convertOutcome{name: in.Name, data: reanimatorData}
+			}
+		}()
+	}
+
+	go func() {
+		defer close(jobs)
+		for i := range inputFiles {
+			jobs <- i
+		}
+	}()
+	wg.Wait()
+
+	for i, out := range results {
+		if out.data == nil {
+			failures = append(failures, out.fail)
 			progress := ((i + 1) * 100) / totalProcess
 			s.jobManager.UpdateJobStatus(jobID, CollectStatusRunning, progress, "")
 			continue
 		}
 
-		entryPath := sanitizeZipPath(in.Name)
+		entryPath := sanitizeZipPath(out.name)
 		entry, err := zw.Create(entryPath + ".reanimator.json")
 		if err != nil {
-			failures = append(failures, fmt.Sprintf("%s: %v", in.Name, err))
+			failures = append(failures, fmt.Sprintf("%s: %v", out.name, err))
 			progress := ((i + 1) * 100) / totalProcess
 			s.jobManager.UpdateJobStatus(jobID, CollectStatusRunning, progress, "")
 			continue
@@ -1464,8 +1504,8 @@ func (s *Server) runConvertJob(jobID, tempDir string, inputFiles []convertInputF
 
 		encoder := json.NewEncoder(entry)
 		encoder.SetIndent("", "  ")
-		if err := encoder.Encode(reanimatorData); err != nil {
-			failures = append(failures, fmt.Sprintf("%s: %v", in.Name, err))
+		if err := encoder.Encode(out.data); err != nil {
+			failures = append(failures, fmt.Sprintf("%s: %v", out.name, err))
 		} else {
 			success++
 		}