v0.4.67: NFSv3 alongside SMB (in-process via nfs3_client crate)

NFS is back — done right this time. v0.4.67 ships a pure-Rust NFSv3
client (`nfs3_client` 0.9 from the xetdata/Vaiz crate family) running
in-process inside the openpxe binary. No `mount.nfs`, no kernel
modules, no `CAP_SYS_ADMIN`, no subprocess. Works in every container
that the v0.4.65 SMB path works in (Unraid included).

The v0.4.65 SMB path stays as-is. Operators get both protocols
side-by-side and pick whichever their NAS prefers — or use both
together. NFSv3 has one architectural advantage over the SMB
userspace path: HTTP Range requests work for NFS-sourced ISOs
because NFSv3 READ3 takes an explicit offset. SMB-sourced ISOs still
return 416 for ranges (smbclient CLI can't seek mid-stream).

## What's new

- `crates/iso-store/src/nfs_share.rs` — `NfsShareManager` mirroring
  `SmbShareManager` structurally. Lists ISOs via READDIR3+LOOKUP3+
  GETATTR3, streams files via READ3 in 64 KiB chunks piped to axum
  body streams. Uses `connect_from_privileged_port(false)` because
  the openpxe binary runs as uid 10001 — most modern NFS servers
  allow that; a server that demands privileged ports needs
  `insecure` in /etc/exports, and the hint translation calls that
  out specifically.
- `IsoSource::Nfs { share_id, relative_path }` variant alongside the
  existing `Smb`. `IsoStore::iso_path_for` returns None for both;
  the HTTP handler dispatches to the right share manager.
- `/api/nfs-shares` CRUD + scan endpoints, parallel to
  `/api/smb-shares`. `POST` body: `{ server, export, port? }`.
- `nfs` terminal command back (this time as in-process, not kernel
  mount): `list | add <srv>:<export> [port] | remove | scan`. The
  v0.4.64 `nfs` command name pointing at kernel mount is moot
  history — same name, completely different mechanism.
- Storage tab: a new NFS shares card sits directly below the SMB
  shares card. The form is simpler (no auth fields) since NFSv3
  uses AUTH_SYS and access is gated server-side by client IP.
- Dashboard "Images available" tile sums SMB + NFS reachable shares
  into a generic "N remote shares" line.

## What's the same

- The structured `{error, stderr, hint}` JSON shape on failures
  matches the SMB API exactly, so the UI's error banner renders
  identically.
- Hint translation: NFS3ERR_ACCES → "exports list", NFS3ERR_NOENT →
  "export path doesn't exist", `mount denied` → "/etc/exports may
  need `insecure`", timeouts → "check IP/port/firewall".
- Persistence: `<work_dir>/nfs_shares.json`. No conflict with the
  long-dead v0.4.64 `nfs.json`.

## Why nfs3_client

User picked it: pure-Rust matches the architecture, NFSv3 covers the
real-world cases, AUTH_SYS keeps the UI simple. The crate is at
0.9.0, MIT/Unlicense, rust-version 1.88 (we're on 1.95). Tokio
feature flag enabled. Image size unchanged at compile time — single
musl static binary, no extra OS packages.

## Tests

160 passing (was 150 in v0.4.66, +10):
- nfs_share parser: stable share ids, server normalization (smb://,
  cifs://, \\, // all stripped).
- hint_for(): NFS3ERR_ACCES, NFS3ERR_NOENT, mount denied, unknown.
- status_label() covers the common nfsstat3 codes.
- HTTP integration: nfs-shares list starts empty, missing server
  rejected, export without leading slash rejected.

`cargo clippy --workspace --all-targets -- -D warnings` clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Cargo.toml

@@ -12,7 +12,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.4.66"
+version = "0.4.67"
 edition = "2021"
 rust-version = "1.95"
 license = "MIT OR Apache-2.0"
@@ -58,6 +58,14 @@ once_cell = "1.19"
 parking_lot = "0.12"
 rust-embed = { version = "8.5", features = ["include-exclude"] }
 
+# v0.4.67: pure-Rust NFSv3 client. Replaces the (deleted-in-v0.4.65)
+# kernel-mount NFS path with an in-process implementation that works
+# in any container — no kernel modules, no CAP_SYS_ADMIN, no
+# subprocess. Ships alongside the userspace SMB consumer; operators
+# pick whichever protocol their NAS prefers.
+nfs3_client = { version = "0.9", features = ["tokio"] }
+nfs3_types = "0.5"
+
 openpxe-core = { path = "crates/core" }
 openpxe-dhcp-proxy = { path = "crates/dhcp-proxy" }
 openpxe-tftp = { path = "crates/tftp" }