Skip RTF header/footer left, right and first-page groups on import

Found while testing crates/textimport/src/rtf.rs:43-63 (SKIP list) and :201 (`SKIP.contains(&word.as_str())`)

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

crates/textimport/src/rtf.rs

@@ -47,7 +47,13 @@ const SKIP: &[&str] = &[
     "info",
     "pict",
     "header",
+    "headerl",
+    "headerr",
+    "headerf",
     "footer",
+    "footerl",
+    "footerr",
+    "footerf",
     "footnote",
     "listtable",
     "listoverridetable",
@@ -310,6 +316,15 @@ fn cp1252(b: u8) -> char {
 mod tests {
     use super::*;
 
+    #[test]
+    fn header_and_footer_variants_are_skipped() {
+        for w in ["header", "headerl", "headerr", "headerf", "footer", "footerl", "footerr", "footerf"] {
+            let rtf = format!(r"{{\rtf1\ansi {{\{w} Page head\par}}Body text\par}}");
+            let text = import(rtf.as_bytes()).unwrap().story.text;
+            assert_eq!(text.trim_end(), "Body text", "{w}");
+        }
+    }
+
     #[test]
     fn out_of_range_unicode_escape_is_dropped() {
         assert_eq!(import(br"{\rtf1 a\u4294967361?b}").unwrap().story.text, "ab");