cleanup: remove Windows native support, enforce WSL requirement

Remove Windows batch scripts and native setup instructions since Claude Code CLI
requires WSL on Windows. Consolidate Docker as primary recommendation across all platforms.

Changes:
- Remove setup.bat, run_gemini.bat, setup-docker-env.bat
- Remove examples/claude_config_windows.json
- Update README to clarify WSL requirement for Windows users
- Promote Docker as recommended setup for all platforms
- Update troubleshooting section for WSL-only support
- Apply code formatting fixes from ruff/black

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

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

utils/file_utils.py

@@ -267,9 +267,7 @@ def resolve_and_validate_path(path_str: str) -> Path:
     # Step 3: Security Policy - Require absolute paths
     # Relative paths could be interpreted differently depending on working directory
     if not user_path.is_absolute():
-        raise ValueError(
-            f"Relative paths are not supported. Please provide an absolute path.\n" f"Received: {path_str}"
-        )
+        raise ValueError(f"Relative paths are not supported. Please provide an absolute path.\nReceived: {path_str}")
 
     # Step 4: Resolve the absolute path (follows symlinks, removes .. and .)
     # This is critical for security as it reveals the true destination of symlinks
@@ -286,9 +284,7 @@ def resolve_and_validate_path(path_str: str) -> Path:
             f"Requested: {path_str}, Resolved: {resolved_path}, Root: {PROJECT_ROOT}"
         )
         raise PermissionError(
-            f"Path outside project root: {path_str}\n"
-            f"Project root: {PROJECT_ROOT}\n"
-            f"Resolved path: {resolved_path}"
+            f"Path outside project root: {path_str}\nProject root: {PROJECT_ROOT}\nResolved path: {resolved_path}"
         )
 
     return resolved_path