Decode numeric tab entities in HTML paste

Found while testing crates/engine/src/cmd/richclip.rs:304 (numeric_char, used by decode_text)

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

crates/engine/src/cmd/richclip.rs

@@ -334,7 +334,7 @@ fn decode_text(raw: &str) -> String {
 fn numeric_char(digits: &str) -> Option<char> {
     let hex = digits.strip_prefix('x').or_else(|| digits.strip_prefix('X'));
     let n = if let Some(hex) = hex { u32::from_str_radix(hex, 16).ok()? } else { digits.parse().ok()? };
-    char::from_u32(n).filter(|c| !c.is_control() || *c == '\n')
+    char::from_u32(n).filter(|c| !c.is_control() || matches!(*c, '\n' | '\t'))
 }
 
 /// Do the HTML's words and the paste's plain text say the same thing?
@@ -352,6 +352,12 @@ fn fold(s: &str) -> String {
 mod tests {
     use super::*;
 
+    #[test]
+    fn numeric_tab_entity_decodes_to_tab() {
+        assert_eq!(decode_text("a&#9;b"), "a\tb");
+        assert_eq!(decode_text("a&#x9;b"), "a\tb");
+    }
+
     #[test]
     fn google_docs_normal_weight_wrapper_is_not_bold() {
         let html = "<meta charset=\"utf-8\"><b style=\"font-weight:normal;\" id=\"docs-internal-guid-1\"><span style=\"font-weight:400\">plain words</span></b>";