fix(cache): allow --help flag for cache subcommand (#3580)

* fix(cache): allow --help flag for cache subcommand

* docs: add changelog entry for cache --help fix

tests/integration_tests.rs

@@ -3684,3 +3684,20 @@ fn quiet_empty_suppresses_output_on_empty_file() {
         .success()
         .stdout("");
 }
+
+#[test]
+fn cache_help_shows_help_message() {
+    // Test that `bat cache --help` works (fixes #3560)
+    // Run in cache_source directory which doesn't have a file named "cache"
+    bat_with_config()
+        .current_dir(Path::new(EXAMPLES_DIR).join("cache_source"))
+        .arg("cache")
+        .arg("--help")
+        .assert()
+        .success()
+        .stdout(predicate::str::contains(
+            "Modify the syntax-definition and theme cache",
+        ))
+        .stdout(predicate::str::contains("--build"))
+        .stdout(predicate::str::contains("--clear"));
+}