fix: use Python 3.9 compatible builtin generics

- Convert List[str] to list[str], Dict[str, Any] to dict[str, Any], etc.
- Use ruff --unsafe-fixes to automatically apply all type annotation updates
- Remove deprecated typing imports (List, Dict, Tuple) where no longer needed
- Keep Optional[str] syntax (union operator | not supported in Python 3.9)

Now all type annotations are Python 3.9 compatible with modern builtin generics.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

packages/leann-backend-diskann/leann_backend_diskann/graph_partition.py

@@ -12,7 +12,7 @@ import shutil
 import subprocess
 import tempfile
 from pathlib import Path
-from typing import Optional, Tuple
+from typing import Optional
 
 
 class GraphPartitioner:
@@ -92,7 +92,7 @@ class GraphPartitioner:
         output_dir: Optional[str] = None,
         partition_prefix: Optional[str] = None,
         **kwargs,
-    ) -> Tuple[str, str]:
+    ) -> tuple[str, str]:
         """
         Partition a disk-based index for improved performance.
 
@@ -267,7 +267,7 @@ def partition_graph(
     partition_prefix: Optional[str] = None,
     build_type: str = "release",
     **kwargs,
-) -> Tuple[str, str]:
+) -> tuple[str, str]:
     """
     Convenience function to partition a graph index.