fix: close rollover planner before Today handoff (Closes #1268)

src/frontend_bundle.py

@@ -95,7 +95,7 @@ def _runtime(frontend_dir: Path, sources: tuple[str, ...], prefix: str) -> Runti
     digest = hashlib.sha256(content).hexdigest()[:16]
     return RuntimeBundle(
         runtime_bytes=content,
-        runtime_gzip_bytes=gzip.compress(content, compresslevel=6, mtime=0),
+        runtime_gzip_bytes=gzip.compress(content, compresslevel=9, mtime=0),
         runtime_digest=digest,
         runtime_name=f"{prefix}-{digest}.js",
     )