feat(search): add configurable sorting for submission results

Introduce a `sort` query parameter in submission search paths and pass it into
store search logic. Matching results can now be ordered by `newest`, `oldest`,
`score_desc`, `score_asc`, `mops_desc`, or `mops_asc`, with invalid values
safely defaulting to `newest`.

Update README and HTTP examples to document the new sort behavior and usage so
clients can control result ordering server-side without extra post-processing.feat(search): add configurable sorting for submission results

Introduce a `sort` query parameter in submission search paths and pass it into
store search logic. Matching results can now be ordered by `newest`, `oldest`,
`score_desc`, `score_asc`, `mops_desc`, or `mops_asc`, with invalid values
safely defaulting to `newest`.

Update README and HTTP examples to document the new sort behavior and usage so
clients can control result ordering server-side without extra post-processing.

lib/store/store.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -116,11 +117,12 @@ func (s *Store) ListSubmissions(page, pageSize int) ([]model.Submission, int) {
 	return results, total
 }
 
-func (s *Store) SearchSubmissions(text, cpu, thread, platform string, intensity, durationSecs int) []model.Submission {
+func (s *Store) SearchSubmissions(text, cpu, thread, platform, sortBy string, intensity, durationSecs int) []model.Submission {
 	queryText := normalizeSearchText(text)
 	cpuText := normalizeSearchText(cpu)
 	thread = normalizeThreadFilter(thread)
 	platform = normalizePlatformFilter(platform)
+	sortBy = normalizeSortOption(sortBy)
 
 	s.mu.RLock()
 	defer s.mu.RUnlock()
@@ -159,6 +161,7 @@ func (s *Store) SearchSubmissions(text, cpu, thread, platform string, intensity,
 		results = append(results, *model.CloneSubmission(record.submission))
 	}
 
+	sortSubmissions(results, sortBy)
 	return results
 }
 
@@ -296,6 +299,70 @@ func normalizePlatformFilter(value string) string {
 	}
 }
 
+func normalizeSortOption(value string) string {
+	switch strings.ToLower(strings.TrimSpace(value)) {
+	case "", "newest":
+		return "newest"
+	case "oldest":
+		return "oldest"
+	case "score_desc":
+		return "score_desc"
+	case "score_asc":
+		return "score_asc"
+	case "mops_desc":
+		return "mops_desc"
+	case "mops_asc":
+		return "mops_asc"
+	default:
+		return "newest"
+	}
+}
+
+func sortSubmissions(submissions []model.Submission, sortBy string) {
+	switch sortBy {
+	case "oldest":
+		sort.SliceStable(submissions, func(i, j int) bool {
+			if submissions[i].SubmittedAt.Equal(submissions[j].SubmittedAt) {
+				return submissions[i].SubmissionID < submissions[j].SubmissionID
+			}
+
+			return submissions[i].SubmittedAt.Before(submissions[j].SubmittedAt)
+		})
+	case "score_desc":
+		sort.SliceStable(submissions, func(i, j int) bool {
+			if submissions[i].Score == submissions[j].Score {
+				return submissions[i].SubmittedAt.After(submissions[j].SubmittedAt)
+			}
+
+			return submissions[i].Score > submissions[j].Score
+		})
+	case "score_asc":
+		sort.SliceStable(submissions, func(i, j int) bool {
+			if submissions[i].Score == submissions[j].Score {
+				return submissions[i].SubmittedAt.After(submissions[j].SubmittedAt)
+			}
+
+			return submissions[i].Score < submissions[j].Score
+		})
+	case "mops_desc":
+		sort.SliceStable(submissions, func(i, j int) bool {
+			if submissions[i].MOpsPerSec == submissions[j].MOpsPerSec {
+				return submissions[i].SubmittedAt.After(submissions[j].SubmittedAt)
+			}
+
+			return submissions[i].MOpsPerSec > submissions[j].MOpsPerSec
+		})
+	case "mops_asc":
+		sort.SliceStable(submissions, func(i, j int) bool {
+			if submissions[i].MOpsPerSec == submissions[j].MOpsPerSec {
+				return submissions[i].SubmittedAt.After(submissions[j].SubmittedAt)
+			}
+
+			return submissions[i].MOpsPerSec < submissions[j].MOpsPerSec
+		})
+	}
+}
+
 func pageBounds(page, pageSize, total int) (int, int, int) {
 	if pageSize <= 0 {
 		pageSize = 50