test(fonts): the u glyph-name form reads with four, five and six digits (hayro-interpret patch 92)

The test of the glyph list's hex forms now has well-formed `u` names too,
so a change that broke that branch of `glyph_text` would fail it. The rule
itself is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pq7HyCHD1R3rywQBPCHXZA

crates/fonts/src/pdf.rs

@@ -1373,6 +1373,9 @@ mod encoding_tests {
         assert_eq!(glyph_text("u65"), None, "`u` takes four to six digits");
         assert_eq!(glyph_text("u0010FFFF"), None);
         assert_eq!(glyph_text("uni0065").as_deref(), Some("e"));
+        assert_eq!(glyph_text("u0065").as_deref(), Some("e"), "`u` and four digits");
+        assert_eq!(glyph_text("u1F600").as_deref(), Some("\u{1f600}"), "`u` and five");
+        assert_eq!(glyph_text("u10FFFF").as_deref(), Some("\u{10ffff}"), "`u` and six, the last code point");
     }
 
     #[test]