feat(types): add "enhancement" as alias for "feature" type

Support --type enhancement as an alias for --type feature when creating
issues. The normalization happens before validation to ensure consistency
across all code paths.

Closes gt-hzanoe

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/quick.go

@@ -66,7 +66,7 @@ Example:
 			Title:     title,
 			Status:    types.StatusOpen,
 			Priority:  priority,
-			IssueType: types.IssueType(issueType),
+			IssueType: types.IssueType(issueType).Normalize(),
 		}
 
 		ctx := rootCtx