feat(viz-platform): create MCP server foundation (#170)

Add viz-platform MCP server structure at mcp-servers/viz-platform/:
- mcp_server/server.py: Main MCP server entry point with async initialization
- mcp_server/config.py: Hybrid config loader with DMC version detection
- mcp_server/dmc_tools.py: Placeholder for DMC validation tools
- pyproject.toml and requirements.txt for dependencies
- tests/ directory structure

Server starts without errors with empty tool list.
Config detects DMC installation status via importlib.metadata.

Closes #170

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mcp-servers/viz-platform/mcp_server/dmc_tools.py

@@ -0,0 +1,72 @@
+"""
+DMC (Dash Mantine Components) validation tools.
+
+Provides component constraint layer to prevent Claude from hallucinating invalid props.
+Tools implemented in Issue #172.
+"""
+import logging
+from typing import Dict, List, Optional, Any
+
+logger = logging.getLogger(__name__)
+
+
+class DMCTools:
+    """
+    DMC component validation tools.
+
+    These tools provide the "constraint layer" that validates component usage
+    against a version-locked registry of DMC components.
+    """
+
+    def __init__(self, registry=None):
+        """
+        Initialize DMC tools with component registry.
+
+        Args:
+            registry: ComponentRegistry instance (from Issue #171)
+        """
+        self.registry = registry
+
+    async def list_components(self, category: Optional[str] = None) -> Dict[str, Any]:
+        """
+        List available DMC components, optionally filtered by category.
+
+        Args:
+            category: Optional category filter (e.g., "inputs", "buttons", "navigation")
+
+        Returns:
+            Dict with components grouped by category
+        """
+        # Implementation in Issue #172
+        raise NotImplementedError("Implemented in Issue #172")
+
+    async def get_component_props(self, component: str) -> Dict[str, Any]:
+        """
+        Get props schema for a specific component.
+
+        Args:
+            component: Component name (e.g., "Button", "TextInput")
+
+        Returns:
+            Dict with props, types, defaults, and enum values
+        """
+        # Implementation in Issue #172
+        raise NotImplementedError("Implemented in Issue #172")
+
+    async def validate_component(
+        self,
+        component: str,
+        props: Dict[str, Any]
+    ) -> Dict[str, Any]:
+        """
+        Validate component props against registry.
+
+        Args:
+            component: Component name
+            props: Props to validate
+
+        Returns:
+            Dict with valid: bool, errors: [], warnings: []
+        """
+        # Implementation in Issue #172
+        raise NotImplementedError("Implemented in Issue #172")