Fix Vue property conflicts in PlatformServiceMixin implementation

- Remove duplicate property declarations from TopMessage component
- Use (this as any) type assertion for mixin methods
- Resolves 'Data property already defined' warnings
- Fixes 'this.dbQuery is not a function' runtime errors

src/services/PlatformService.ts

@@ -137,8 +137,5 @@ export interface PlatformService {
    * @param params - The parameters to pass to the query
    * @returns Promise resolving to the first row as an array, or undefined if no results
    */
-  dbGetOneRow(
-    sql: string,
-    params?: unknown[],
-  ): Promise<unknown[] | undefined>;
+  dbGetOneRow(sql: string, params?: unknown[]): Promise<unknown[] | undefined>;
 }