Adds an `rclone://<remote>/<path>` scheme backed by the rclone CLI, giving
yazi native browsing of any of rclone's 100+ remotes (S3, GCS, Azure, SFTP,
WebDAV, local, …) without a FUSE mount.
- New SchemeKind::Rclone threaded through the scheme/URL type system,
mirroring Sftp (remote, virtual, Unix-path, byte-encoded path semantics).
- yazi-vfs rclone provider:
- read_dir via `rclone lsjson`
- metadata via `rclone lsjson --stat` (synthesized POSIX mode)
- seekable read-only File streaming `rclone cat --offset`; seek respawns
the child at the new offset. Detects premature EOF and unknown sizes.
- all write ops return Unsupported (read-only for now)
- `remote:/path` targets preserve the leading slash, so filesystem-like
backends (local, sftp) work alongside object stores.
- Config: [services.<name>] type = "rclone", remote = "..."
- Tests:
- tests/rclone_local.rs: hermetic, points an rclone `local` remote at a
temp fixture dir, so it needs no cloud/credentials and skips if `rclone`
isn't installed. Covers list, read, seek, missing-object, and a >8 MiB
parallel multi-chunk copy with position-varying bytes.
- tests/rclone_read.rs: env-driven live tests against a real remote
(ignored by default; paths supplied via env vars, nothing hard-coded).
