Consolidate server utilities into shared module

- Add lib/server/utils/normalize.ts with normalizeTicker, normalizeTagsOrNull, nowIso, todayIso
- Add lib/server/utils/validation.ts with asRecord, asBoolean, asStringArray, asEnum
- Add lib/server/utils/index.ts re-exporting all utilities
- Remove duplicate lib/server/utils.ts (old file)
- Update all repos and files to use shared utilities
- Remove redundant ?? '' from normalizeTicker calls
- Update watchlist.ts to use normalizeTagsOrNull for null-return tags

lib/server/yahoo-company-profile.ts

@@ -1,3 +1,5 @@
+import { normalizeTicker } from '@/lib/server/utils';
+
 type FetchImpl = typeof fetch;
 
 type CacheEntry<T> = {
@@ -142,7 +144,7 @@ export async function getYahooCompanyDescription(
   ticker: string,
   options?: { fetchImpl?: FetchImpl }
 ) {
-  const normalizedTicker = ticker.trim().toUpperCase();
+  const normalizedTicker = normalizeTicker(ticker);
   if (!normalizedTicker) {
     return null;
   }