Fix S&P 500 universe parse so renames like BNY are discovered.

Wikipedia no longer uses plain symbol table cells; parse exchange links and NyseSymbol templates, surface the list source in bootstrap results, and keep legacy cell parsing as a fallback.

frontend/src/lib/types.ts

@@ -718,10 +718,14 @@ export interface TickerUniverseSetting {
 
 export interface TickerUniverseBootstrapResult {
   universe: TickerUniverse;
+  /** Where the member list came from: wikipedia_sp500 | fmp | cache | seed | … */
+  source?: string;
   total_universe_symbols: number;
   added: number;
   already_tracked: number;
   deleted: number;
+  /** Sample of newly added symbols (capped server-side). */
+  added_symbols?: string[];
 }
 
 export interface PipelineReadiness {