feat(api): support optional systemInfo in submissions

Extend the submission contract to accept a `systemInfo` object and persist it with each submission, including deep-copy support for `extra` metadata.

Also update client-facing docs and HTTP examples (JSON and multipart) and document that the schema is available at `GET /api/schema`, so clients can reliably implement the updated payload format.feat(api): support optional systemInfo in submissions

Extend the submission contract to accept a `systemInfo` object and persist it with each submission, including deep-copy support for `extra` metadata.

Also update client-facing docs and HTTP examples (JSON and multipart) and document that the schema is available at `GET /api/schema`, so clients can reliably implement the updated payload format.

lib/store/store.go

@@ -66,12 +66,13 @@ func (s *Store) Count() int {
 	return len(s.orderedIDs)
 }
 
-func (s *Store) SaveSubmission(result model.BenchmarkResult, submitter, platform string) (*model.Submission, error) {
+func (s *Store) SaveSubmission(result model.BenchmarkResult, submitter, platform string, systemInfo *model.SystemInfo) (*model.Submission, error) {
 	submission := &model.Submission{
 		SubmissionID:    uuid.NewString(),
 		Submitter:       model.NormalizeSubmitter(submitter),
 		Platform:        model.NormalizePlatform(platform),
 		SubmittedAt:     time.Now().UTC(),
+		SystemInfo:      cloneSystemInfo(systemInfo),
 		BenchmarkResult: result,
 	}
 
@@ -97,6 +98,22 @@ func (s *Store) SaveSubmission(result model.BenchmarkResult, submitter, platform
 	return model.CloneSubmission(submission), nil
 }
 
+func cloneSystemInfo(info *model.SystemInfo) *model.SystemInfo {
+	if info == nil {
+		return nil
+	}
+
+	copyInfo := *info
+	if len(info.Extra) > 0 {
+		copyInfo.Extra = make(map[string]any, len(info.Extra))
+		for key, value := range info.Extra {
+			copyInfo.Extra[key] = value
+		}
+	}
+
+	return &copyInfo
+}
+
 func (s *Store) ListSubmissions(page, pageSize int) ([]model.Submission, int) {
 	s.mu.RLock()
 	defer s.mu.RUnlock()