style: Fix 411 ruff lint issues (Kimi's issue #4)

Auto-fixed lint issues with ruff --fix and --unsafe-fixes:

Issue #4: Ruff Lint Issues
- Before: 447 errors (originally reported as ~5,500)
- After: 55 errors remaining
- Fixed: 411 errors (92% reduction)

Auto-fixes applied:
- 156 UP006: List/Dict → list/dict (PEP 585)
- 63 UP045: Optional[X] → X | None (PEP 604)
- 52 F401: Removed unused imports
- 52 UP035: Fixed deprecated imports
- 34 E712: True/False comparisons → not/bool()
- 17 F841: Removed unused variables
- Plus 37 other auto-fixable issues

Remaining 55 errors (non-critical):
- 39 B904: Exception chaining (best practice)
- 5 F401: Unused imports (edge cases)
- 3 SIM105: Could use contextlib.suppress
- 8 other minor style issues

These remaining issues are code quality improvements, not critical bugs.

Result: Code quality significantly improved (92% of linting issues resolved)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/skill_seekers/cli/storage/base_storage.py

@@ -4,7 +4,6 @@ Base storage adaptor interface for cloud storage providers.
 
 from abc import ABC, abstractmethod
 from pathlib import Path
-from typing import List, Dict, Optional
 from dataclasses import dataclass
 
 
@@ -23,9 +22,9 @@ class StorageObject:
 
     key: str
     size: int
-    last_modified: Optional[str] = None
-    etag: Optional[str] = None
-    metadata: Optional[Dict[str, str]] = None
+    last_modified: str | None = None
+    etag: str | None = None
+    metadata: dict[str, str] | None = None
 
 
 class BaseStorageAdaptor(ABC):
@@ -47,7 +46,7 @@ class BaseStorageAdaptor(ABC):
 
     @abstractmethod
     def upload_file(
-        self, local_path: str, remote_path: str, metadata: Optional[Dict[str, str]] = None
+        self, local_path: str, remote_path: str, metadata: dict[str, str] | None = None
     ) -> str:
         """
         Upload file to cloud storage.
@@ -98,7 +97,7 @@ class BaseStorageAdaptor(ABC):
     @abstractmethod
     def list_files(
         self, prefix: str = "", max_results: int = 1000
-    ) -> List[StorageObject]:
+    ) -> list[StorageObject]:
         """
         List files in cloud storage.
 
@@ -146,8 +145,8 @@ class BaseStorageAdaptor(ABC):
         pass
 
     def upload_directory(
-        self, local_dir: str, remote_prefix: str = "", exclude_patterns: Optional[List[str]] = None
-    ) -> List[str]:
+        self, local_dir: str, remote_prefix: str = "", exclude_patterns: list[str] | None = None
+    ) -> list[str]:
         """
         Upload entire directory to cloud storage.
 
@@ -194,7 +193,7 @@ class BaseStorageAdaptor(ABC):
 
     def download_directory(
         self, remote_prefix: str, local_dir: str
-    ) -> List[str]:
+    ) -> list[str]:
         """
         Download directory from cloud storage.