feat(core): add base accessor method for conda channel support

Add get_python_dependency_channel() method to PackageAccessorBase to
support retrieving conda channel information from package metadata.
This provides the foundation for v1.2.2 schema which introduces
conda package manager support with optional channel specification.

The method returns None by default, allowing version-specific
accessors to override with appropriate implementation.

Author: LittleCoinCoin

hatch_validator/core/pkg_accessor_base.py

@@ -347,3 +347,23 @@ def get_citations(self, metadata: Dict[str, Any]) -> Any:
         if self.next_accessor:
             return self.next_accessor.get_citations(metadata)
         raise NotImplementedError("Citations accessor not implemented for this schema version")
+
+    def get_python_dependency_channel(self, dependency: Dict[str, Any]) -> Any:
+        """Get channel from a Python dependency.
+
+        This method is only available for schema versions >= 1.2.2 which support
+        conda package manager with channel specification.
+
+        Args:
+            dependency (Dict[str, Any]): Python dependency object
+
+        Returns:
+            Any: Channel value (e.g., "conda-forge", "bioconda")
+
+        Raises:
+            NotImplementedError: If there is no next accessor and this method is not overridden,
+                                or if the schema version does not support channels
+        """
+        if self.next_accessor:
+            return self.next_accessor.get_python_dependency_channel(dependency)
+        raise NotImplementedError("Python dependency channel accessor not implemented for this schema version")