perf(move-file): cache index file export analysis

[LayZeeDK]

Summary

Cache export information for index files so isFileExported() and related checks avoid reparsing the same files during a batch move.

Proposed Solution

interface IndexExports {
  exports: Set<string>;
  reexports: Set<string>;
}

const indexExportsCache = new Map<string, IndexExports>();

function getIndexExports(tree: Tree, indexPath: string): IndexExports {
  const cached = indexExportsCache.get(indexPath);
  if (cached !== undefined) {
    return cached;
  }

  const exports = new Set<string>();
  const reexports = new Set<string>();

  const ast = astCache.getAST(tree, indexPath);
  if (ast) {
    // Parse and extract all exports
    // ... parsing logic ...
  }

  const result = { exports, reexports };
  indexExportsCache.set(indexPath, result);
  return result;
}

• Cache parsed export lists for index/barrel files.
• Consult the cache before re-parsing index files.

Tasks

• Create an IndexExports cache keyed by normalized index file paths
• Populate the cache via existing AST/content helpers on first access
• Update export-checking utilities to consult the cache before re-reading

Definition of Done

• Existing benchmark and stress test suites are run before and after the change; share the comparison in the PR description. This step cannot be skipped.
• Unit/e2e tests must still pass.
• Add inline docs describing the cache lifecycle if helpful.