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/smb_share.rs

@@ -231,10 +231,7 @@ impl SmbShareManager {
 
     /// Add or refresh a share. Validates the input, writes a creds
     /// file, probes connectivity, and scans for ISOs.
-    pub async fn add(
-        &self,
-        req: SmbAddRequest,
-    ) -> std::result::Result<SmbShare, SmbShareError> {
+    pub async fn add(&self, req: SmbAddRequest) -> std::result::Result<SmbShare, SmbShareError> {
         let server = normalize_server(&req.server);
         let share = req.share.trim().trim_start_matches('/').to_string();
         if server.is_empty() {
@@ -309,7 +306,9 @@ impl SmbShareManager {
         if let Err(e) = self.rescan_inner(&id).await {
             let m = self.get(&id);
             return Err(SmbShareError {
-                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),
@@ -365,11 +364,7 @@ impl SmbShareManager {
     /// throttling concurrent smbclients) would need to await without
     /// changing the call sites.
     #[allow(clippy::unused_async)]
-    pub async fn stream_iso(
-        &self,
-        share_id: &str,
-        filename: &str,
-    ) -> Result<SmbStream> {
+    pub async fn stream_iso(&self, share_id: &str, filename: &str) -> Result<SmbStream> {
         let share = self
             .get(share_id)
             .ok_or_else(|| Error::Invalid(format!("no such SMB share '{share_id}'")))?;
@@ -377,9 +372,7 @@ impl SmbShareManager {
         // share root. smbclient itself accepts only filenames at the
         // share root in our `get` form, but belt-and-suspenders.
         if filename.contains('/') || filename.contains('\\') || filename.contains("..") {
-            return Err(Error::Invalid(format!(
-                "invalid filename '{filename}'"
-            )));
+            return Err(Error::Invalid(format!("invalid filename '{filename}'")));
         }
         let creds = share
             .creds_path
@@ -537,10 +530,7 @@ impl SmbShareManager {
                 } else {
                     String::new()
                 };
-                return Err((
-                    format!("could not exec smbclient: {e}"),
-                    stderr,
-                ));
+                return Err((format!("could not exec smbclient: {e}"), stderr));
             }
         };
         if !output.status.success() {
@@ -751,10 +741,7 @@ fn parse_ls_iso(out: &str) -> Vec<SmbListEntry> {
 
 /// Pre-flight TCP probe to `server:port`. Format matches v0.4.64 NFS
 /// probe so the UI banner reads consistently.
-async fn tcp_probe(
-    server: &str,
-    port: u16,
-) -> std::result::Result<(), (String, String)> {
+async fn tcp_probe(server: &str, port: u16) -> std::result::Result<(), (String, String)> {
     use tokio::net::TcpStream;
     let addr = format!("{server}:{port}");
     match tokio::time::timeout(PROBE_TIMEOUT, TcpStream::connect(&addr)).await {
@@ -931,8 +918,8 @@ mod tests {
         // exec error in `error` plus an empty `stderr`. The
         // SmbShareError constructor's hint_for fallback checks error
         // too, so this pattern needs to translate as well.
-        let h2 = hint_for("could not exec smbclient: No such file or directory (os error 2)")
-            .unwrap();
+        let h2 =
+            hint_for("could not exec smbclient: No such file or directory (os error 2)").unwrap();
         assert!(h2.contains("smbclient"));
     }