docs(hopper): document HopperTargetLease realpath fallback

Closes #642

src/hopper/HopperTargetLease.ts

@@ -35,6 +35,12 @@ export const acquireHopperTargetLease = async (input: {
 }): Promise<HopperTargetLeaseAcquisition> => {
   const directory = input.directory ?? leaseDirectory;
   await ensureLeaseDirectory(directory);
+  // The canonical path only derives the lease key; it never authorizes access.
+  // `realpath` is expected to fail when the target or a path component is
+  // missing (ENOENT, ENOTDIR), unreadable (EACCES), or a symlink loop (ELOOP).
+  // The lexical `resolve` fallback still yields a deterministic key, so the
+  // only cost is that symlinked spellings of such a path may take separate
+  // leases.
   const targetPath = await realpath(input.targetPath).catch(() =>
     resolve(input.targetPath),
   );