clawhdf5-remote: clippy clean with every feature set

checked_div in the test server's throttle, a slice for the single range
of fetch_first, and dead-code allowances for the redaction helpers in a
build with neither http nor a cloud store.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

crates/clawhdf5-remote/src/error.rs

@@ -66,12 +66,20 @@ pub fn redact_url(url: &str) -> String {
 /// Replaces the secret parts of one URL (its userinfo and query string,
 /// and the URL itself) wherever they appear in a message — such as the
 /// text of an error from the HTTP client.
+#[cfg_attr(
+    not(any(feature = "http", feature = "s3", feature = "gcs", feature = "azure")),
+    allow(dead_code)
+)]
 #[derive(Debug, Clone)]
 pub(crate) struct Redactor {
     shown: String,
     secrets: Vec<(String, String)>,
 }
 
+#[cfg_attr(
+    not(any(feature = "http", feature = "s3", feature = "gcs", feature = "azure")),
+    allow(dead_code)
+)]
 impl Redactor {
     pub(crate) fn new(url: &str) -> Redactor {
         let shown = redact_url(url);
@@ -177,7 +185,10 @@ pub enum RemoteError {
 
 impl RemoteError {
     /// The error with every secret part of `r`'s URL scrubbed from its text.
-    #[cfg_attr(not(any(feature = "http", feature = "object-store")), allow(dead_code))]
+    #[cfg_attr(
+        not(any(feature = "http", feature = "s3", feature = "gcs", feature = "azure")),
+        allow(dead_code)
+    )]
     pub(crate) fn scrubbed(self, r: &Redactor) -> RemoteError {
         let f = |s: String| r.scrub(&s);
         match self {

crates/clawhdf5-remote/src/object.rs

@@ -140,7 +140,10 @@ impl ObjectStoreStorage {
 
     /// The object's first `n` bytes (fewer if it is shorter).
     pub(crate) fn fetch_first(&self, n: u64) -> Result<Vec<u8>, RemoteError> {
-        Ok(self.fetch_all(&[0..n])?.pop().unwrap_or_default())
+        Ok(self
+            .fetch_all(std::slice::from_ref(&(0..n)))?
+            .pop()
+            .unwrap_or_default())
     }
 
     fn fetch_all(&self, ranges: &[Range<u64>]) -> Result<Vec<Vec<u8>>, RemoteError> {

crates/clawhdf5-remote/tests/common/server.rs

@@ -405,8 +405,8 @@ fn serve(conn: TcpStream, s: &Shared) -> std::io::Result<()> {
             for piece in rest.chunks(4096) {
                 out.write_all(piece)?;
                 out.flush()?;
-                if bps > 0 {
+                if let Some(us) = (4096 * 1_000_000u64).checked_div(bps) {
-                    std::thread::sleep(Duration::from_micros(4096 * 1_000_000 / bps));
+                    std::thread::sleep(Duration::from_micros(us));
                 }
             }
         } else {