refactor(tables): tidy lazy ref init and align perf-rule cross-reference

- use-workspace-imports: lazy-init the status Map at its point of use in
  the effect ((ref.current ??= new Map())) instead of mutating the ref
  during render with a separate in-effect fallback. The ref is only read
  in the effect, so this removes the render-phase write and the dead
  '?? new Map()' branch while keeping the identical persistent Map.
- CLAUDE.md: fix the render-performance pointer so it matches the rule
  doc — toSorted/toReversed are unsafe on client render paths (SWC does
  not polyfill prototype methods), not merely an ES2022/ES2023 lib note.

Author: waleedlatif1

CLAUDE.md

@@ -127,7 +127,7 @@ export function Component({ requiredProp, optionalProp = false }: ComponentProps
 
 Extract when: 50+ lines, used in 2+ files, or has own state/logic. Keep inline when: < 10 lines, single use, purely presentational.
 
-Behavior-preserving render-performance idioms — lazy-init object refs, hoist closure-free values/functions to module scope, pre-index repeated lookups with `Map`/`Set`, and immutable array methods (`toSorted`) with the ES2022-vs-ES2023 lib caveat — are in `.claude/rules/sim-react-performance.md`. For the render-timing effect/state anti-patterns use the `/you-might-not-need-*` skills and verify against the running UI.
+Behavior-preserving render-performance idioms — lazy-init object refs, hoist closure-free values/functions to module scope, pre-index repeated lookups with `Map`/`Set`, and never mutating a shared array in place — are in `.claude/rules/sim-react-performance.md` (which also explains why `toSorted`/`toReversed` are unsafe on client render paths despite the ES2023 tsconfig lib — SWC does not polyfill prototype methods, so use `[...arr].sort()`). For the render-timing effect/state anti-patterns use the `/you-might-not-need-*` skills and verify against the running UI.
 
 ## API Contracts
 

apps/sim/app/workspace/[workspaceId]/tables/components/import-progress-menu/use-workspace-imports.ts

@@ -52,10 +52,9 @@ export function useWorkspaceImports(
   const { data: exportJobs } = useWorkspaceExportJobs(workspaceId)
 
   const prevStatusRef = useRef<Map<string, string> | null>(null)
-  prevStatusRef.current ??= new Map()
   useEffect(() => {
     if (!tables) return
-    const prevStatus = prevStatusRef.current ?? new Map<string, string>()
+    const prevStatus = (prevStatusRef.current ??= new Map())
     const store = useImportTrayStore.getState()
     for (const table of tables) {
       const before = prevStatus.get(table.id)