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/utils/waypoint-utils.ts

@@ -100,7 +100,7 @@ export class WaypointUtils {
 		try {
 			const content = await vault.read(file);
 			hasWaypoint = this.hasWaypointMarker(content);
-		} catch (error) {
+		} catch {
 			// If we can't read the file, we can't check for waypoints
 		}