fix: correct FastMCP interface usage and resolve lint issues

- Fix FastMCP server interface to use correct mcp.run() instead of app.run(host, port)
- Remove unnecessary host and port parameters, use standard STDIO transport
- Fix all ruff lint issues including import sorting and blank lines
- Update ruff configuration to new lint configuration format
- Fix type annotation issues using Union syntax (int | None)
- Ensure uvx pypi-query-mcp-server works correctly
- All tests pass and lint checks pass

pypi_query_mcp/core/exceptions.py

@@ -4,7 +4,7 @@
 class PyPIError(Exception):
     """Base exception for PyPI-related errors."""
 
-    def __init__(self, message: str, status_code: int = None):
+    def __init__(self, message: str, status_code: int | None = None):
         super().__init__(message)
         self.message = message
         self.status_code = status_code
@@ -22,7 +22,7 @@ class PackageNotFoundError(PyPIError):
 class NetworkError(PyPIError):
     """Raised when network-related errors occur."""
 
-    def __init__(self, message: str, original_error: Exception = None):
+    def __init__(self, message: str, original_error: Exception | None = None):
         super().__init__(message)
         self.original_error = original_error
 
@@ -30,7 +30,7 @@ class NetworkError(PyPIError):
 class RateLimitError(PyPIError):
     """Raised when API rate limit is exceeded."""
 
-    def __init__(self, retry_after: int = None):
+    def __init__(self, retry_after: int | None = None):
         message = "PyPI API rate limit exceeded"
         if retry_after:
             message += f". Retry after {retry_after} seconds"
@@ -50,7 +50,7 @@ class InvalidPackageNameError(PyPIError):
 class PyPIServerError(PyPIError):
     """Raised when PyPI server returns a server error."""
 
-    def __init__(self, status_code: int, message: str = None):
+    def __init__(self, status_code: int, message: str | None = None):
         if not message:
             message = f"PyPI server error (HTTP {status_code})"
         super().__init__(message, status_code=status_code)