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]>

crates/openpxe/src/main.rs

@@ -9,7 +9,7 @@ use openpxe_core::{
 };
 use openpxe_dhcp_proxy::DhcpProxyServer;
 use openpxe_http_api::{build_router, AppState};
-use openpxe_iso_store::{IsoStore, SmbManager, SmbShareManager};
+use openpxe_iso_store::{IsoStore, NfsShareManager, SmbManager, SmbShareManager};
 use openpxe_tftp::TftpServer;
 use std::net::{Ipv4Addr, SocketAddr};
 use std::path::PathBuf;
@@ -133,6 +133,18 @@ async fn main() -> anyhow::Result<()> {
         );
     }
 
+    // v0.4.67: NFSv3 share manager — pure-Rust in-process consumer
+    // via the `nfs3_client` crate. Sits alongside the SMB manager;
+    // operators pick whichever protocol their NAS prefers, or use
+    // both. No subprocess, no kernel mount, works in any container.
+    let nfs_shares = NfsShareManager::new(&config.paths.work_dir, iso_store.clone());
+    if let Err(e) = nfs_shares.load_and_rescan().await {
+        tracing::warn!(
+            target: "openpxe::nfs",
+            "could not reload NFS shares on startup: {e}"
+        );
+    }
+
     // Sniff network details for the Network tab. None of these are
     // required for PXE to work — they're informational, surfaced in the
     // UI so an operator doesn't have to drop to a shell to find their
@@ -158,6 +170,7 @@ async fn main() -> anyhow::Result<()> {
         metrics: metrics.clone(),
         smb: Some(smb.clone()),
         smb_shares: smb_shares.clone(),
+        nfs_shares: nfs_shares.clone(),
         uploads: openpxe_http_api::uploads::UploadSessions::default(),
         log_bus: log_bus.clone(),
         started_at: time::OffsetDateTime::now_utc(),