fix(schema): terminate generated JSON with a trailing newline

pretty-format-json (pre-commit) rewrites schema/schema.json and schema/meta.json
because gen_all wrote them via json.dumps(indent=2) with no trailing newline.
Content is otherwise identical to the hook's output, so add the newline in
download_schema (keeping regeneration idempotent) and to the committed files.

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

Author: michelTho

schema/meta.json

@@ -49,4 +49,4 @@
   "protocolMethods": {
     "cancel_request": "$/cancel_request"
   }
-}
+}

schema/schema.json

@@ -10229,4 +10229,4 @@
       "x-method": "$/cancel_request"
     }
   }
-}
+}

scripts/gen_all.py

@@ -140,8 +140,8 @@ def download_schema(repo: str, ref: str) -> None:
         print(exc, file=sys.stderr)
         sys.exit(1)
 
-    SCHEMA_JSON.write_text(json.dumps(schema_data, indent=2), encoding="utf-8")
-    META_JSON.write_text(json.dumps(meta_data, indent=2), encoding="utf-8")
+    SCHEMA_JSON.write_text(json.dumps(schema_data, indent=2) + "\n", encoding="utf-8")
+    META_JSON.write_text(json.dumps(meta_data, indent=2) + "\n", encoding="utf-8")
     VERSION_FILE.write_text(ref + "\n", encoding="utf-8")
     print(f"Fetched schema and meta from {repo}@{ref}")