Add basic sync support to the agentfs CLI

[sivukhin]

This PR depends on the PR tursodatabase/turso#4359

This PR makes it possible to use sync for tursodb in CLI and FUSE layer.

$> cat sync.config
{
    "remote_url": "libsql://<db>-<org>.turso.io",
    "auth_token": "...",
    "partial_sync_experimental": {"segment_size": 131072, "prefetch": true, "bootstrap_strategy": {"type": "prefix", "length": 131072}}
}
$> agentfs init partial-sync-v1 --sync-config-path sync.config
$> agentfs mount partial-sync-v1 --sync-config-path sync.config ./mount-point
$> cd ./mount-point
$ ls
CHANGELOG.md  MANUAL.md  README.md  SPEC.md  TESTING.md  cli  dist-workspace.toml  examples  sandbox  scripts  sdk
$> cat .fuse.sync.status # special file with sync information
{"cdc_operations":0,"main_wal_size":8264,"revert_wal_size":0,"last_pull_unix_time":1766651125,"last_push_unix_time":1766651125,"revision":"{\"generation\":999999999999999998,\"wal_fragment_no\":0}","network_sent_bytes":0,"network_received_bytes":0}
$> echo 'push' > .fuse.sync.control
$> echo 'pull' > .fuse.sync.control
$> echo 'checkpoint' > .fuse.sync.control