fix(tools): filter self and cls parameters from @beta_tool schema generation

[Ashutosh0x]

fix(tools): filter self and cls parameters from @beta_tool schema generation

Summary

This PR enables class methods and instance methods to be used with the @beta_tool decorator by filtering out self and cls parameters from the generated JSON schema.

Problem

When using @beta_tool on a class method or instance method, the generated JSON schema incorrectly includes self or cls as required parameters, causing validation errors.

Solution

Modified kw_arguments_schema in _beta_functions.py to filter out self and cls parameters from both the properties and required fields of the generated schema.

Example

class MyTools:
    def __init__(self, user_id: int):
        self.user_id = user_id

    @beta_tool
    def get_user_info(self, query: str) -> str:
        """Get user information.
        
        Args:
            query: The query string to search for
        """
        return f"User {self.user_id}: {query}"

# Now works correctly - 'self' is not in the schema
tools = MyTools(user_id=123)
print(tools.get_user_info.input_schema)
# {'properties': {'query': {...}}, 'required': ['query'], ...}

Fixes #1087