Fix -n flag to show line numbers in loop-through mode

When the -n/--number flag is passed on the command line, bat now shows
line numbers even when piping output to another process (loop-through
mode), similar to how `cat -n` behaves.

This change detects if -n or --number was passed on the CLI (before
merging with config file and environment variables) and disables
loop-through mode in that case, allowing the InteractivePrinter to
add line numbers.

The existing behavior is preserved:
- Styles from config/env are still ignored when piping (unless --decorations=always is set)
- Only the -n flag from CLI enables line numbers in piped mode
- -p and --style options from CLI do not disable loop-through mode

tests/integration_tests.rs

@@ -166,6 +166,17 @@ fn line_numbers() {
         .stdout("   1 line 1\n   2 line 2\n   3 line 3\n   4 line 4\n   5 line 5\n   6 line 6\n   7 line 7\n   8 line 8\n   9 line 9\n  10 line 10\n");
 }
 
+// Test that -n on command line shows line numbers even when piping (similar to `cat -n`)
+#[test]
+fn line_numbers_from_cli_in_loop_through_mode() {
+    bat()
+        .arg("multiline.txt")
+        .arg("-n")
+        .assert()
+        .success()
+        .stdout("   1 line 1\n   2 line 2\n   3 line 3\n   4 line 4\n   5 line 5\n   6 line 6\n   7 line 7\n   8 line 8\n   9 line 9\n  10 line 10\n");
+}
+
 #[test]
 fn line_range_2_3() {
     bat()
@@ -419,8 +430,8 @@ fn piped_output_with_line_numbers_style_flag() {
 }
 
 #[test]
-#[cfg(not(target_os = "windows"))]
 fn piped_output_with_line_numbers_with_header_grid_style_flag() {
+    // style ignored because non-interactive
     bat()
         .arg("--style=header,grid,numbers")
         .write_stdin("hello\nworld\n")