fix: keep large-file editing responsive

Bound synchronous full-source syntax parsing, cache dirty comparisons, edit ordinary inline changes in place, retain changed-row undo history, and buffer atomic saves. Skip repository snapshots beyond existing worker limits before copying their text.

src/editor_review.rs

@@ -109,6 +109,7 @@ impl Editor {
                 .is_some_and(|binding| binding.owner == self.tab_id)
             {
                 buffer.saved_lines.clone_from(&buffer.lines);
+                buffer.dirty_cache.set(Some(false));
             }
         }
     }
@@ -268,6 +269,7 @@ impl Editor {
             }) {
                 buffer.review_buffer = None;
                 buffer.saved_lines.clone_from(&buffer.lines);
+                buffer.dirty_cache.set(Some(false));
             }
         }
         self.autosave_local_review()?;
@@ -849,6 +851,7 @@ impl Editor {
                 self.active.lines = split_lines(text);
                 self.active.saved_lines.clone_from(&self.active.lines);
                 self.active.text_revision = self.active.text_revision.wrapping_add(1);
+                self.active.dirty_cache.set(Some(false));
                 self.normalize_targets();
             }
         } else {