fix(tools): h5rs diff names its options as h5diff does

-c meant "list at most N differences" in h5rs, but in h5diff -c is
--compare (a flag) and the count is -n/--count=N, so a script moved over
from h5diff behaved differently: `h5diff -r -c 2 A B` exits 2 (the 2 is
taken as a file name) while h5rs exited 1.

The count is now -n/--count, -c/--compare is accepted (h5rs always lists
objects that are not comparable), and the --count=N, --delta=D,
--relative=R forms are accepted; exit codes equal h5diff's on 7 cases.

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

crates/clawhdf5-tools/src/cli.rs

@@ -11,30 +11,37 @@ pub struct Out<'a> {
 /// The arguments after the subcommand name.
 pub struct Args {
     cmd: &'static str,
-    rest: std::vec::IntoIter<String>,
+    rest: std::collections::VecDeque<String>,
 }
 
 impl Args {
     pub fn new(cmd: &'static str, rest: Vec<String>) -> Self {
         Self {
             cmd,
-            rest: rest.into_iter(),
+            rest: rest.into(),
         }
     }
 
     #[allow(clippy::should_implement_trait)]
     pub fn next(&mut self) -> Option<String> {
-        self.rest.next()
+        self.rest.pop_front()
+    }
+
+    /// Put an option and its value back, to be read next (for the
+    /// `--name=value` form).
+    pub fn push_front(&mut self, name: String, value: String) {
+        self.rest.push_front(value);
+        self.rest.push_front(name);
     }
 
     /// The value after an option such as `--max-bytes`.
     pub fn value(&mut self) -> Option<String> {
-        self.rest.next()
+        self.rest.pop_front()
     }
 
     /// A numeric option value.
     pub fn number<T: std::str::FromStr>(&mut self) -> Option<T> {
-        self.rest.next().and_then(|s| s.parse().ok())
+        self.rest.pop_front().and_then(|s| s.parse().ok())
     }
 
     /// Report a usage problem; exit status 2.