test: improve coverage for models and toolset modules (76% → 87%) (#67)

* refactor(toolset): remove unused _matches_filter method

Remove the _matches_filter method from StackOneToolSet as it was
never called in the source code (only used in tests). This reduces
code complexity and improves test coverage percentage.

The existing _filter_by_provider and _filter_by_action methods
provide equivalent functionality and are actually used in fetch_tools.

* test: improve coverage for models and toolset modules

Add comprehensive tests for previously uncovered code paths:

models.py (78% -> 95%):
- validate_method unsupported HTTP method error
- ExecuteConfig validation
- Parameter location handling (PATH, QUERY, BODY)
- HTTP error handling (JSON and text response bodies)
- RequestError handling
- Non-dict response wrapping
- OpenAI conversion (enum, array, object, non-dict properties)
- LangChain conversion (number, integer, boolean types)
- Async _arun method
- Tools container iteration and account ID methods

toolset.py (52% -> 77%):
- _StackOneRpcTool execution (basic, JSON string, payloads)
- Header handling (Authorization stripping, None value skipping)
- Argument parsing edge cases

Overall coverage improved from 76% to 87%.

Author: ryoppippi

stackone_ai/toolset.py

@@ -253,34 +253,6 @@ def __init__(
         self.base_url = base_url or DEFAULT_BASE_URL
         self._account_ids: list[str] = []
 
-    def _matches_filter(self, tool_name: str, filter_pattern: str | list[str]) -> bool:
-        """Check if a tool name matches the filter pattern
-
-        Args:
-            tool_name: Name of the tool to check
-            filter_pattern: String or list of glob patterns to match against.
-                          Patterns starting with ! are treated as negative matches.
-
-        Returns:
-            True if the tool name matches any positive pattern and no negative patterns,
-            False otherwise
-        """
-        patterns = [filter_pattern] if isinstance(filter_pattern, str) else filter_pattern
-
-        # Split into positive and negative patterns
-        positive_patterns = [p for p in patterns if not p.startswith("!")]
-        negative_patterns = [p[1:] for p in patterns if p.startswith("!")]
-
-        # If no positive patterns, treat as match all
-        matches_positive = (
-            any(fnmatch.fnmatch(tool_name, p) for p in positive_patterns) if positive_patterns else True
-        )
-
-        # If any negative pattern matches, exclude the tool
-        matches_negative = any(fnmatch.fnmatch(tool_name, p) for p in negative_patterns)
-
-        return matches_positive and not matches_negative
-
     def set_accounts(self, account_ids: list[str]) -> StackOneToolSet:
         """Set account IDs for filtering tools