Track strikethrough (SGR 9) so it is not dropped across highlighted tokens

The `Attributes` ANSI style tracker in `src/vscreen.rs` declares, initializes,
clears (in `sgr_reset`), and re-emits (in `Display`) a `strike` field
documented as `ON: ^[9m / OFF: ^[29m`, but `update_with_sgr()` had no match
arm for SGR 9 (set strikethrough) or 29 (clear strikethrough). As a result
`strike` was only ever cleared, never set.

Because bat re-applies the tracked input ANSI style before each highlighted
text run (nu_ansi_term appends a full reset after every token), attributes
that are tracked — bold, dim, italic, underline — survive across tokens,
while strikethrough was silently dropped after the first token. This path is
active by default (`--strip-ansi`/`--sanitize` default to `never`).

Add the missing `9` and `29` arms, mirroring the sibling underline (4/24) and
italic (3/23) arms, so strikethrough is tracked and re-emitted like every
other supported attribute.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/integration_tests.rs

@@ -3355,6 +3355,25 @@ fn ansi_sgr_joins_attributes_when_wrapped() {
             .stderr("");
 }
 
+// Ensure that strikethrough (SGR 9) is tracked like the other attributes, so it is
+// re-emitted (and therefore preserved) across a wrap boundary instead of being dropped.
+#[test]
+fn ansi_sgr_strike_joins_attributes_when_wrapped() {
+    bat()
+            .arg("--paging=never")
+            .arg("--color=never")
+            .arg("--terminal-width=20")
+            .arg("--wrap=character")
+            .arg("--decorations=always")
+            .arg("--style=plain")
+            .write_stdin("\x1B[33mColor. \x1B[9mStrike.......Struck+color.\n")
+            .assert()
+            .success()
+            .stdout("\x1B[33m\x1B[33mColor. \x1B[9m\x1B[33m\x1B[9mStrike.......\n\x1B[33m\x1B[9mStruck+color.\n")
+            // FIXME:              ~~~~~~~~       ~~~~~~~~~~~~~~~ should not be emitted twice.
+            .stderr("");
+}
+
 #[test]
 fn ignored_suffix_arg() {
     bat()