Reject a sign after # in EPS PostScript radix numbers

Found while testing crates/eps/src/import/lex.rs:287-289 (number)

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/eps/src/import/lex.rs

@@ -286,6 +286,10 @@ fn number(w: &str) -> Option<Obj> {
     }
     if let Some((base, digits)) = w.split_once('#') {
         let base: u32 = base.parse().ok().filter(|b| (2..=36).contains(b))?;
+        // `from_str_radix` accepts a leading sign; a PostScript radix number has digits only.
+        if digits.starts_with(['+', '-']) {
+            return None;
+        }
         return i64::from_str_radix(digits, base).ok().map(Obj::Int);
     }
     // Rust reads `inf` and `nan`; PostScript doesn't.
@@ -295,3 +299,15 @@ fn number(w: &str) -> Option<Obj> {
     let v: f64 = w.parse().ok()?;
     v.is_finite().then_some(Obj::Real(v))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn radix_number_with_sign_after_hash_is_not_a_number() {
+        assert!(number("16#+ff").is_none());
+        assert!(number("16#-ff").is_none());
+        assert!(matches!(number("16#ff"), Some(Obj::Int(255))));
+    }
+}