[Fix] Enable AST chunking when installed (package chunking utils) (#101)

* fix(core): package chunking utils for AST chunking; re-export in apps; CLI imports packaged utils

* style

* chore: fix ruff warnings (RUF059, F401)

* style

apps/chunking/__init__.py

@@ -1,16 +1,38 @@
-"""
-Chunking utilities for LEANN RAG applications.
-Provides AST-aware and traditional text chunking functionality.
+"""Unified chunking utilities facade.
+
+This module re-exports the packaged utilities from `leann.chunking_utils` so
+that both repo apps (importing `chunking`) and installed wheels share one
+single implementation. When running from the repo without installation, it
+adds the `packages/leann-core/src` directory to `sys.path` as a fallback.
 """
 
-from .utils import (
-    CODE_EXTENSIONS,
-    create_ast_chunks,
-    create_text_chunks,
-    create_traditional_chunks,
-    detect_code_files,
-    get_language_from_extension,
-)
+import sys
+from pathlib import Path
+
+try:
+    from leann.chunking_utils import (
+        CODE_EXTENSIONS,
+        create_ast_chunks,
+        create_text_chunks,
+        create_traditional_chunks,
+        detect_code_files,
+        get_language_from_extension,
+    )
+except Exception:  # pragma: no cover - best-effort fallback for dev environment
+    repo_root = Path(__file__).resolve().parents[2]
+    leann_src = repo_root / "packages" / "leann-core" / "src"
+    if leann_src.exists():
+        sys.path.insert(0, str(leann_src))
+        from leann.chunking_utils import (
+            CODE_EXTENSIONS,
+            create_ast_chunks,
+            create_text_chunks,
+            create_traditional_chunks,
+            detect_code_files,
+            get_language_from_extension,
+        )
+    else:
+        raise
 
 __all__ = [
     "CODE_EXTENSIONS",