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/recent-developments.ts

@@ -1,5 +1,6 @@
 import { format } from 'date-fns';
 import type { Filing, RecentDevelopmentItem, RecentDevelopments } from '@/lib/types';
+import { normalizeTicker } from '@/lib/server/utils';
 
 export type RecentDevelopmentSourceContext = {
   filings: Filing[];
@@ -115,9 +116,9 @@ export async function getRecentDevelopments(
     limit?: number;
   }
 ): Promise<RecentDevelopments> {
-  const normalizedTicker = ticker.trim().toUpperCase();
+  const normalizedTicker = normalizeTicker(ticker);
   const limit = options?.limit ?? 6;
-  const cacheKey = `${normalizedTicker}:${context.filings.map((filing) => filing.accession_number).join(',')}`;
+  const cacheKey = `${normalizedTicker ?? ''}:${context.filings.map((filing) => filing.accession_number).join(',')}`;
   const cached = recentDevelopmentsCache.get(cacheKey);
 
   if (cached && cached.expiresAt > Date.now()) {
@@ -128,7 +129,7 @@ export async function getRecentDevelopments(
   const itemCollections = await Promise.all(
     sources.map(async (source) => {
       try {
-        return await source.fetch(normalizedTicker, context);
+        return await source.fetch(normalizedTicker ?? '', context);
       } catch {
         return [] satisfies RecentDevelopmentItem[];
       }