refactor(filer): remove the inode->path index and the NFS gateway (#9724)

* fix(filer): derive inodes by hash instead of a snowflake sequencer

Compute the same inode the FUSE mount would: non-hard-linked entries hash path + crtime, hard links hash their shared HardLinkId so every link resolves to one inode. Removes the snowflake inodeSequencer and the SEAWEEDFS_FILER_SNOWFLAKE_ID knob; inodes are now deterministic across filers.

* chore: remove the experimental NFS gateway

The NFS frontend ('weed nfs') was the only consumer of the inode->path index. Remove the weed/server/nfs package, the command and its registration, the integration test harness, and the CI workflow; go mod tidy drops the willscott/go-nfs and go-nfs-client dependencies.

* refactor(filer): drop the inode->path index

With the NFS gateway gone, nothing reads it. A regular file's inode is a pure hash of its path and a hard link's is a hash of its shared HardLinkId -- both derivable on demand -- so the secondary KV index and its write/remove hooks are dead. Removes filer_inode_index.go and the recordInodeIndex hooks from the store wrapper.

weed/command/command.go

@@ -48,7 +48,6 @@ var Commands = []*Command{
 	cmdVolume,
 	cmdWebDav,
 	cmdSftp,
-	cmdNfs,
 	cmdWorker,
 }