Fix LSP test to accommodate expanded keyword completions

The upstream merge added 10 new VCL-total keywords to completions
(GROUP BY, ORDER BY, HAVING, LIMIT, OFFSET, EFFECTS, PROOF ATTACHED,
AT VERSION, CONSUME AFTER, USAGE LIMIT). Update the test assertion
to check that all items are keywords rather than hardcoding the count.

https://claude.ai/code/session_01FxxUVqL8xdA34j7n3Ep52S

Author: claude

src/interface/lsp/src/lib.rs

@@ -487,11 +487,16 @@ mod tests {
         let lsp = VqlutLsp::new();
         let result = lsp.handle_completion(make_completion_params(0, 0));
         if let Some(CompletionResponse::Array(items)) = result {
-            assert_eq!(
-                items.len(),
-                3,
-                "without schema, only 3 keywords expected, got {}",
-                items.len()
+            // All items should be keywords (no schema tables/columns).
+            assert!(
+                items
+                    .iter()
+                    .all(|i| i.kind == Some(CompletionItemKind::KEYWORD)),
+                "without schema, all items should be keywords"
+            );
+            assert!(
+                !items.is_empty(),
+                "should return at least some keyword completions"
             );
         }
     }