fix(sdk): add index signature to UatItem so callers accepting Record<string, unknown>[] compile (#3184)

The 16 TDD cycles passed vitest but tsc --noEmit flagged TS2322:
UatItem lacked a string index signature, so the consumer at
phase-uat-passed.ts:249 (returning Record<string, unknown>[])
failed to typecheck. Index signature added; behaviour unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

sdk/src/query/phase-uat-passed.ts

@@ -51,6 +51,7 @@ const UAT_ITEM_PATTERN =
   /###\s*(\d+)\.\s*([^\n]+)\n(?:\*\*)?expected:(?:\*\*)?\s*([^\n]+)\n(?:\*\*)?result:(?:\*\*)?\s*(\w+)/g;
 
 interface UatItem {
+  [key: string]: unknown;
   test: number;
   name: string;
   expected: string;