perf(move-file): cache relative import specifiers

[LayZeeDK]

Summary

Cache the results of getRelativeImportSpecifier() so repeated file pair lookups reuse previously computed relative paths.

Proposed Solution

const relativePathCache = new Map<string, string>();

function getCachedRelativeImportSpecifier(
  fromFile: string,
  toFile: string,
): string {
  const cacheKey = `${fromFile}|${toFile}`;

  let result = relativePathCache.get(cacheKey);
  if (result === undefined) {
    result = getRelativeImportSpecifier(fromFile, toFile);
    relativePathCache.set(cacheKey, result);
  }

  return result;
}

• Normalise file paths before building the cache key.
• Clear the cache for every generator execution.

Tasks

• Create a cache keyed by normalized file pair strings
• Ensure all relative specifier calculations go through the cache helper
• Clear the cache each generator execution to avoid stale paths

Definition of Done

• Existing benchmark and stress test suites are run before and after the change; include the metrics in the PR description. This is a mandatory check.
• Unit/e2e tests remain successful.
• Document the cache behaviour if needed.