v0.6.2: Mythos Validation — full-codebase polish, hot-path optimizations, dhcproto 0.15

Codebase-wide review pass: finish or remove every loose end, take the
safe performance wins on the serving hot paths, and refresh the
dependency tree for reliability. No behavior changes for working
clients; legacy clients get clearer protocol errors.

Finalize / cleanup:
- Remove mac_allowlist/subnet_allowlist config fields — parsed but never
  enforced since introduction; the operator wants line-of-sight serving,
  so the honest fix is deletion, not wiring.
- Remove dead ClientRegistry API (get, set_selected_target,
  always-None selected_target field, never-emitted DhcpRequest/
  HttpIsoAsset events).
- TFTP: reject WRQ with ERR_ILLEGAL_OP and non-octet modes with a clear
  error instead of silent timeouts (legacy-client friendliness); fold
  plan_window into cfg(test); drop the unused-constant keep-alive hack.
- rustfmt sweep over the six files with accumulated drift.

Hot-path optimizations (all behavior-preserving):
- Serve embedded iPXE binaries zero-copy (Cow over rodata) on both TFTP
  and HTTP — was a ~1 MiB heap copy per boot file request.
- Cache the composited PXE boot-menu background PNG keyed on the
  branding logo revision — was ~50-200 ms of image work per booting
  client; now one compose per logo change.
- Run bcrypt verify/hash on the blocking pool (boot password gate,
  login, setup, credential rotation) so CPU-heavy auth can't stall the
  workers streaming ISO ranges to imaging machines.
- iso_raw: reuse the already-cloned IsoMeta for path resolution instead
  of a second registry lock + deep clone per range request.
- DriverEscalation: amortize the TTL sweep (1-min interval + inline
  staleness check) instead of an O(map) retain per DHCP packet.
- format_mac: one allocation instead of four per datagram.
- Introspection haystack sized to min(scan cap, file size) — was
  guaranteed a 32 MiB realloc on every large-ISO probe.

Robustness:
- parse_range: malformed Range headers are now ignored per RFC 7233
  (200 + full body) instead of answered with a bogus 206.

Dependencies:
- dhcproto 0.12 -> 0.15: drops the deprecated/unmaintained
  trust-dns-proto from the tree (hickory-proto), three releases of DHCP
  option coverage. Compiles + passes the full suite unchanged.
- socket2 0.6 (dedupes tree), bcrypt 0.19, tower-http 0.6.11 (sheds
  iri-string), tokio 1.52.3 / hyper 1.10 lockfile refresh; dead nom
  workspace entry removed; requested versions synced to shipped reality.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

crates/iso-store/src/nfs_share.rs

@@ -63,8 +63,8 @@ use bytes::Bytes;
 use nfs3_client::tokio::TokioConnector;
 use nfs3_client::Nfs3ConnectionBuilder;
 use nfs3_types::nfs3::{
-    self as nfs3, diropargs3, entry3, filename3, nfs_fh3, GETATTR3args, LOOKUP3args,
-    Nfs3Result, READ3args, READDIR3args,
+    self as nfs3, diropargs3, entry3, filename3, nfs_fh3, GETATTR3args, LOOKUP3args, Nfs3Result,
+    READ3args, READDIR3args,
 };
 use nfs3_types::rpc::{auth_unix, opaque_auth};
 use nfs3_types::xdr_codec::Opaque;
@@ -220,10 +220,7 @@ impl NfsShareManager {
     /// Register an NFS share. Validates, probes connectivity by
     /// performing a real MOUNT3 + READDIR3, and registers the
     /// resulting ISOs with the store.
-    pub async fn add(
-        &self,
-        req: NfsAddRequest,
-    ) -> std::result::Result<NfsShare, NfsShareError> {
+    pub async fn add(&self, req: NfsAddRequest) -> std::result::Result<NfsShare, NfsShareError> {
         let server = normalize_server(&req.server);
         let export = req.export.trim().to_string();
         if server.is_empty() {
@@ -258,7 +255,9 @@ impl NfsShareManager {
         if let Err(e) = self.rescan_inner(&id).await {
             let m = self.get(&id);
             return Err(NfsShareError {
-                error: m.as_ref().and_then(|m| m.last_error.clone())
+                error: m
+                    .as_ref()
+                    .and_then(|m| m.last_error.clone())
                     .unwrap_or_else(|| e.to_string()),
                 stderr: String::new(),
                 hint: m.and_then(|m| m.last_hint),
@@ -333,8 +332,7 @@ impl NfsShareManager {
             return Err(Error::Invalid(format!("invalid filename '{filename}'")));
         }
 
-        let (tx, rx) =
-            tokio::sync::mpsc::channel::<std::io::Result<Bytes>>(STREAM_BUFFER_DEPTH);
+        let (tx, rx) = tokio::sync::mpsc::channel::<std::io::Result<Bytes>>(STREAM_BUFFER_DEPTH);
         let server = share.server.clone();
         let export = share.export.clone();
         let port = share.port;
@@ -358,16 +356,11 @@ impl NfsShareManager {
             if let Err(e) = result {
                 // Best-effort signal of the error to the consumer.
                 // If the receiver has already dropped we just exit.
-                let _ = tx
-                    .send(Err(std::io::Error::other(e.to_string())))
-                    .await;
+                let _ = tx.send(Err(std::io::Error::other(e.to_string()))).await;
             }
         });
 
-        Ok(NfsStream {
-            rx,
-            _task: task,
-        })
+        Ok(NfsStream { rx, _task: task })
     }
 
     // ── internals ─────────────────────────────────────────────────────
@@ -982,8 +975,14 @@ mod tests {
         // the allow-list and the secure/insecure angle.
         let h = hint_for("connect failed: MNT3ERR_ACCES").unwrap();
         let lc = h.to_lowercase();
-        assert!(lc.contains("insecure") || lc.contains("privileged"), "got: {h}");
-        assert!(lc.contains("allow") || lc.contains("permission"), "got: {h}");
+        assert!(
+            lc.contains("insecure") || lc.contains("privileged"),
+            "got: {h}"
+        );
+        assert!(
+            lc.contains("allow") || lc.contains("permission"),
+            "got: {h}"
+        );
     }
 
     #[test]