refactor: simplify Phase 1 infrastructure code

- cache-invalidation: extract isExpectedRevalidateError helper
- integration-data-cache: flatten early-return chain, extract eviction
- redis-handler: extract StoredEntry type, readStreamBody, ensureConnected
- svg-purify: single getOwnPropertyDescriptor lookup per prop
- session-scoped-providers: simplify auth flow
- retryable-loader: use function declarations
- translation/request: replace spread-in-reduce with for loop

packages/common/src/retryable-loader.ts

@@ -1,7 +1,7 @@
-export const createRetryableLoader = <TKey, TValue>(loaders: ReadonlyMap<TKey, () => Promise<TValue>>) => {
+export function createRetryableLoader<TKey, TValue>(loaders: ReadonlyMap<TKey, () => Promise<TValue>>) {
   const promises = new Map<TKey, Promise<TValue>>();
 
-  return (key: TKey) => {
+  return function load(key: TKey) {
     const existing = promises.get(key);
     if (existing) return existing;
 
@@ -15,4 +15,4 @@ export const createRetryableLoader = <TKey, TValue>(loaders: ReadonlyMap<TKey, (
     });
     return promise;
   };
-};
+}