fix: address ObsidianReviewBot linting issues

- Add type guard for recursive parameter in notifications.ts to ensure
  only boolean values are stringified (prevents [object Object] output)
- Remove unused error variables from catch blocks across 5 files:
  - vault-tools.ts (5 instances)
  - frontmatter-utils.ts (3 instances)
  - search-utils.ts (2 instances)
  - waypoint-utils.ts (1 instance)

src/ui/notifications.ts

@@ -162,8 +162,8 @@ export class NotificationManager {
 			if (args.folder && typeof args.folder === 'string') {
 				keyParams.push(`folder: "${this.truncateString(args.folder, 30)}"`);
 			}
-			if (args.recursive !== undefined) {
-				keyParams.push(`recursive: ${String(args.recursive)}`);
+			if (typeof args.recursive === 'boolean') {
+				keyParams.push(`recursive: ${args.recursive}`);
 			}
 
 			// If no key params, show first 50 chars of JSON