perf(move-file): cache file import metadata

[LayZeeDK]

Summary

Cache lightweight import/export metadata for files touched by the move-file generator so that repeated checks avoid unnecessary reads and AST work.

Proposed Solution

interface FileMetadata {
  hasImports: boolean;
  hasExports: boolean;
  knownSpecifiers: Set<string>;
}

const fileMetadataCache = new Map<string, FileMetadata>();

function getFileMetadata(tree: Tree, filePath: string): FileMetadata {
  const cached = fileMetadataCache.get(filePath);
  if (cached !== undefined) {
    return cached;
  }

  const content = astCache.getContent(tree, filePath);
  if (!content) {
    return { hasImports: false, hasExports: false, knownSpecifiers: new Set() };
  }

  const metadata: FileMetadata = {
    hasImports: content.includes('import') || content.includes('require'),
    hasExports: content.includes('export'),
    knownSpecifiers: extractSpecifiers(content),
  };

  fileMetadataCache.set(filePath, metadata);
  return metadata;
}

• Populate metadata on first access using cached file content.
• Consult metadata before re-reading or re-parsing files.

Tasks

• Define a FileMetadata structure and cache keyed by normalized file path
• Populate metadata on first access using the existing content/AST cache
• Update import-related helpers to leverage the cached metadata before re-reading files

Definition of Done

• Existing benchmark and stress test suites are run before and after the change; document the findings in the PR description. Skipping this is not allowed.
• Unit/e2e tests must pass.
• Add comments/tests to cover the metadata cache lifecycle if necessary.