refactor: dedupe shared string readers

src/shared/record-coerce.ts

@@ -4,6 +4,14 @@ export function asRecord(value: unknown): Record<string, unknown> {
   return typeof value === "object" && value !== null ? (value as Record<string, unknown>) : {};
 }
 
+export function readStringField(
+  record: Record<string, unknown> | null | undefined,
+  key: string,
+): string | undefined {
+  const value = record?.[key];
+  return typeof value === "string" ? value : undefined;
+}
+
 export function asOptionalRecord(value: unknown): Record<string, unknown> | undefined {
   return isRecord(value) ? value : undefined;
 }

src/shared/string-coerce.ts

@@ -1,3 +1,7 @@
+export function readStringValue(value: unknown): string | undefined {
+  return typeof value === "string" ? value : undefined;
+}
+
 export function normalizeNullableString(value: unknown): string | null {
   if (typeof value !== "string") {
     return null;