fix: resolve import ordering and type annotation style issues

Clean up import statements and type annotations to ensure CI lint compliance:
- Reorder imports alphabetically where appropriate
- Update type annotations to use modern union syntax (str | int instead of Union[str, int])
- Fix metadata processing type hints for ChromaDB compatibility

All quality checks pass locally:
✅ Tests: 35 passed, 2 skipped
✅ Lint: No violations (F,E9 checks)
✅ Type check: mypy clean

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

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

Author: MementoRC

src/uckn/core/__init__.py

@@ -1,6 +1,6 @@
 """UCKN Core Module - Main components for knowledge management."""
 
-from .atoms.semantic_search import SemanticSearch, SEMANTIC_SEARCH_ENGINE_AVAILABLE
+from .atoms.semantic_search import SEMANTIC_SEARCH_ENGINE_AVAILABLE, SemanticSearch
 from .organisms.knowledge_manager import KnowledgeManager
 
 # Expose for backward compatibility with tests

src/uckn/core/atoms/semantic_search.py

@@ -3,8 +3,8 @@
 """
 
 import logging
-from typing import Any
 from pathlib import Path
+from typing import Any
 
 try:
     from ..semantic_search import SemanticSearchEngine

src/uckn/storage/chromadb_connector.py

@@ -1,6 +1,6 @@
 import logging
 from pathlib import Path
-from typing import Any, Dict, List, Union, Type
+from typing import Any
 
 try:
     import chromadb
@@ -124,8 +124,8 @@ def _validate_partial_metadata(self, collection_name: str, metadata: dict[str, A
             self._logger.error(f"No schema defined for collection: {collection_name}")
             return False
 
-        metadata_types: Dict[str, Any] = schema["metadata_types"]  # type: ignore
-        
+        metadata_types: dict[str, Any] = schema["metadata_types"]  # type: ignore
+
         # Only validate the fields that are provided, don't require all fields for updates
         for key, value in metadata.items():
             expected_type = metadata_types.get(key)
@@ -137,9 +137,9 @@ def _validate_partial_metadata(self, collection_name: str, metadata: dict[str, A
                 return False
         return True
 
-    def _process_metadata_for_chromadb(self, metadata: dict[str, Any]) -> dict[str, Union[str, int, float]]:
+    def _process_metadata_for_chromadb(self, metadata: dict[str, Any]) -> dict[str, str | int | float]:
         """Process metadata to make it compatible with ChromaDB constraints."""
-        processed: Dict[str, Union[str, int, float]] = {}
+        processed: dict[str, str | int | float] = {}
         for key, value in metadata.items():
             if isinstance(value, list):
                 # Convert lists to comma-separated strings for ChromaDB compatibility
@@ -161,10 +161,10 @@ def _restore_metadata_from_chromadb(self, collection_name: str, metadata: dict[s
         schema = self._COLLECTION_SCHEMAS.get(collection_name)
         if not schema:
             return metadata
-        
-        restored: Dict[str, Any] = {}
-        metadata_types: Dict[str, Any] = schema["metadata_types"]  # type: ignore
-        
+
+        restored: dict[str, Any] = {}
+        metadata_types: dict[str, Any] = schema["metadata_types"]  # type: ignore
+
         for key, value in metadata.items():
             expected_type = metadata_types.get(key)
             if expected_type == list and isinstance(value, str):
@@ -306,13 +306,13 @@ def update_document(
 
         try:
             collection = self.collections[collection_name]
-            
+
             # Auto-update the updated_at timestamp if metadata is being updated
             if metadata is not None:
                 from datetime import datetime
                 metadata = metadata.copy()  # Don't modify the original
                 metadata["updated_at"] = datetime.now().isoformat()
-            
+
             processed_metadata = self._process_metadata_for_chromadb(metadata) if metadata is not None else None
             collection.update(
                 ids=[doc_id],