Extract duplicate path processing logic from handleTryFiles,
handleInternalRedirect, and handleStandard into two new methods:
- stripPathPrefix(): zero-allocation path prefix stripping
- buildFilePath(): build full file path supporting alias/root modes
This reduces code duplication and makes the path handling logic
easier to maintain.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>