fix(block-editing): satisfy clippy -D warnings gate in nested-buffer code

Two lints the workspace clippy gate (added on main) denies:
- regenerate_nested_buffers.rs: map_or(false, ..) -> is_some_and(..)
- regenerate_nested_buffers_tests.rs: map(..).unwrap_or_else(panic) -> match

Author: gordonwoodhull

crates/pampa/src/regenerate_nested_buffers.rs

@@ -173,7 +173,7 @@ fn maybe_emit(block: &Block, content: &str, out: &mut BTreeMap<String, String>)
     // final character. Every block offset range includes the block's trailing
     // newline, so `slice.contains('\n')` would match all single-line blocks.
     // We skip the last byte to detect only genuine continuation lines.
-    let is_multiline = content.as_bytes().get(start..end).map_or(false, |b| {
+    let is_multiline = content.as_bytes().get(start..end).is_some_and(|b| {
         let body = if b.last() == Some(&b'\n') {
             &b[..b.len() - 1]
         } else {

crates/pampa/tests/integration/regenerate_nested_buffers_tests.rs

@@ -19,9 +19,10 @@ use quarto_source_map::SourceInfo;
 // =============================================================================
 
 fn parse_qmd(content: &str) -> pampa::pandoc::Pandoc {
-    qmd_to_pandoc(content.as_bytes())
-        .map(|(pandoc, _ctx)| pandoc)
-        .unwrap_or_else(|errs| panic!("Failed to parse QMD: {errs:?}"))
+    match qmd_to_pandoc(content.as_bytes()) {
+        Ok((pandoc, _ctx)) => pandoc,
+        Err(errs) => panic!("Failed to parse QMD: {errs:?}"),
+    }
 }
 
 fn parse_qmd_with_context(content: &str) -> (pampa::pandoc::Pandoc, ASTContext) {