Fix hyphenated issue prefix detection (#199)

- update prefix/number parsing to use the last hyphen across utils and nodb paths
- add regression tests covering multi-hyphen prefixes in both packages

internal/utils/issue_id.go

@@ -7,20 +7,20 @@ import (
 
 // ExtractIssuePrefix extracts the prefix from an issue ID like "bd-123" -> "bd"
 func ExtractIssuePrefix(issueID string) string {
-	parts := strings.SplitN(issueID, "-", 2)
-	if len(parts) < 2 {
+	idx := strings.LastIndex(issueID, "-")
+	if idx <= 0 {
 		return ""
 	}
-	return parts[0]
+	return issueID[:idx]
 }
 
 // ExtractIssueNumber extracts the number from an issue ID like "bd-123" -> 123
 func ExtractIssueNumber(issueID string) int {
-	parts := strings.SplitN(issueID, "-", 2)
-	if len(parts) < 2 {
+	idx := strings.LastIndex(issueID, "-")
+	if idx < 0 || idx == len(issueID)-1 {
 		return 0
 	}
 	var num int
-	fmt.Sscanf(parts[1], "%d", &num)
+	fmt.Sscanf(issueID[idx+1:], "%d", &num)
 	return num
 }