fix: use readlink(2) instead of realpath(3) to avoid autofs stalls invirtiofs paths

[Ronitsabhaya75]

When a host directory under /home/<user>/ is bind-mounted into a container, any code that called URL.resolvingSymlinksInPath() on a path inside that directory would stall for 5–10 seconds. macOS intercepts filesystem lookups under /home/ through its autofs automounter when the code tried to resolve a symlink pointing there, macOS would attempt an automount that never succeeds, timing out after 5–10 seconds.

The fix introduces a rawSymlinkTarget() helper on URL that uses readlink(2) directly. This reads only the raw value stored in the symlink inode — no filesystem traversal, no autofs trigger.