mount: document purpose and fix misleading comment

Add README.md explaining the network transparency role of the mount
package. Replace 'kept as a convenience' comment with one that explains
why it exists and how it differs from local 9pfuse.

cmd/olliesrv/main.go

@@ -90,7 +90,8 @@ func (c *ModelCache) Invalidate() {
 func main() {
 	flag.CommandLine.Parse(os.Args[1:]) //nolint:errcheck
 
-	// Handle mount subcommand (kept as a convenience)
+	// Handle mount subcommand — FUSE-mounts a remote 9P server over TCP
+	// for network-transparent session access (distinct from local 9pfuse)
 	if flag.NArg() > 0 && flag.Arg(0) == "mount" {
 		cmdMount()
 		return

mount/README.md

@@ -0,0 +1,23 @@
+# mount/
+
+FUSE-based 9P mount for network-transparent session access.
+
+## Why this exists
+
+The local workflow uses `9pfuse` (via `ollie-remount`) to mount the unix
+socket at `~/mnt/ollie`. That only works locally.
+
+This package enables **remote** access: `olliesrv mount host:9564 ~/mnt/remote`
+FUSE-mounts a remote 9P server over TCP so sessions on another machine appear
+as local files. No SSH tunneling, no port forwarding, no API gateway — just
+mount and interact.
+
+This is the network transparency layer that makes ollie a distributed system
+rather than a local daemon.
+
+## Not dead code
+
+Nothing in the repo *calls* this package at runtime automatically — it's
+invoked manually via `olliesrv mount`. If you're grepping for callers and
+find only one, that's correct. The value is in the capability, not the
+call count.