fix(typescript): tighten TypeScript null safety and error handling across backend and ops UI

ts/cache/classes.cache.cleaner.ts

@@ -48,14 +48,14 @@ export class CacheCleaner {
     this.isRunning = true;
 
     // Run cleanup immediately on start
-    this.runCleanup().catch((error) => {
-      logger.log('error', `Initial cache cleanup failed: ${error.message}`);
+    this.runCleanup().catch((error: unknown) => {
+      logger.log('error', `Initial cache cleanup failed: ${(error as Error).message}`);
     });
 
     // Schedule periodic cleanup
     this.cleanupInterval = setInterval(() => {
-      this.runCleanup().catch((error) => {
-        logger.log('error', `Cache cleanup failed: ${error.message}`);
+      this.runCleanup().catch((error: unknown) => {
+        logger.log('error', `Cache cleanup failed: ${(error as Error).message}`);
       });
     }, this.options.intervalMs);
 
@@ -113,8 +113,8 @@ export class CacheCleaner {
           `Cache cleanup completed. Deleted ${totalDeleted} expired documents. ${summary || 'No deletions.'}`
         );
       }
-    } catch (error) {
-      logger.log('error', `Cache cleanup error: ${error.message}`);
+    } catch (error: unknown) {
+      logger.log('error', `Cache cleanup error: ${(error as Error).message}`);
       throw error;
     }
   }
@@ -138,14 +138,14 @@ export class CacheCleaner {
         try {
           await doc.delete();
           deletedCount++;
-        } catch (deleteError) {
-          logger.log('warn', `Failed to delete expired document: ${deleteError.message}`);
+        } catch (deleteError: unknown) {
+          logger.log('warn', `Failed to delete expired document: ${(deleteError as Error).message}`);
         }
       }
 
       return deletedCount;
-    } catch (error) {
-      logger.log('error', `Error cleaning collection: ${error.message}`);
+    } catch (error: unknown) {
+      logger.log('error', `Error cleaning collection: ${(error as Error).message}`);
       return 0;
     }
   }