DRY pass #3: checklist near-misses live in the grammar fixture (#5373)

test_notes.py and derive.rs each kept the same six lines of prose that look
like a checklist item. Four were already task_lines cases in grammar.json;
the other two (empty brackets, no bullet) join them, so the web suite now
tests them too, and both hand lists go.

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

core/src/local/derive.rs

@@ -611,21 +611,6 @@ mod tests {
         assert_eq!(extract_items(body), vec![item("middle", false, 1)]);
     }
 
-    #[test]
-    fn items_reject_near_misses() {
-        // Each of these is prose, and each has been someone's bug report somewhere.
-        for body in [
-            "-[ ] no space after the dash",
-            "- [] empty brackets",
-            "- [ ]no space after the brackets",
-            "- [y] not a mark",
-            "a [ ] mid sentence",
-            "[ ] no bullet at all",
-        ] {
-            assert!(extract_items(body).is_empty(), "should be prose: {body}");
-        }
-    }
-
     #[test]
     fn items_accept_star_bullets_and_indentation() {
         // `*` because markdown.ts already takes it for a plain bullet.