Optimize bd list: replace N+1 label queries with bulk fetch

Problem:
In direct mode, bd list was making a separate GetLabels() call for
each issue when displaying labels. With 538 issues, this resulted in
538 separate database queries.

While investigating the reported 5+ second slowness, discovered this
N+1 query issue that would impact performance with many issues.

Solution:
1. Added GetLabelsForIssues(issueIDs []string) to Storage interface
2. Implemented bulk fetch in SQLite (already existed, now exposed)
3. Implemented bulk fetch in MemoryStorage
4. Updated list.go to fetch all labels in single query

Changes:
- internal/storage/storage.go: Add GetLabelsForIssues to interface
- internal/storage/memory/memory.go: Implement GetLabelsForIssues
- cmd/bd/list.go: Use bulk fetching in all output modes

Impact:
Eliminates N queries for labels, replacing with 1 bulk query.
This optimization applies to direct mode only (daemon mode already
uses bulk operations via RPC).

Note: The reported 5s slowness was actually caused by daemon auto-start
timeout. Use --no-daemon flag or run 'bd migrate --update-repo-id' to
resolve the legacy database issue causing daemon startup failures.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

cmd/bd/list.go

@@ -339,18 +339,19 @@ var listCmd = &cobra.Command{
 		}
 
 		if jsonOutput {
-			// Populate labels for JSON output
-			for _, issue := range issues {
-				issue.Labels, _ = store.GetLabels(ctx, issue.ID)
-			}
-
-			// Get dependency counts in bulk (single query instead of N queries)
+			// Get labels and dependency counts in bulk (single query instead of N queries)
 			issueIDs := make([]string, len(issues))
 			for i, issue := range issues {
 				issueIDs[i] = issue.ID
 			}
+			labelsMap, _ := store.GetLabelsForIssues(ctx, issueIDs)
 			depCounts, _ := store.GetDependencyCounts(ctx, issueIDs)
 
+			// Populate labels for JSON output
+			for _, issue := range issues {
+				issue.Labels = labelsMap[issue.ID]
+			}
+
 			// Build response with counts
 			issuesWithCounts := make([]*types.IssueWithCounts, len(issues))
 			for i, issue := range issues {
@@ -368,12 +369,18 @@ var listCmd = &cobra.Command{
 			return
 		}
 
+		// Load labels in bulk for display
+		issueIDs := make([]string, len(issues))
+		for i, issue := range issues {
+			issueIDs[i] = issue.ID
+		}
+		labelsMap, _ := store.GetLabelsForIssues(ctx, issueIDs)
+
 		if longFormat {
 			// Long format: multi-line with details
 			fmt.Printf("\nFound %d issues:\n\n", len(issues))
 			for _, issue := range issues {
-				// Load labels for display
-				labels, _ := store.GetLabels(ctx, issue.ID)
+				labels := labelsMap[issue.ID]
 
 				fmt.Printf("%s [P%d] [%s] %s\n", issue.ID, issue.Priority, issue.IssueType, issue.Status)
 				fmt.Printf("  %s\n", issue.Title)
@@ -388,8 +395,7 @@ var listCmd = &cobra.Command{
 		} else {
 			// Compact format: one line per issue
 			for _, issue := range issues {
-				// Load labels for display
-				labels, _ := store.GetLabels(ctx, issue.ID)
+				labels := labelsMap[issue.ID]
 
 				labelsStr := ""
 				if len(labels) > 0 {