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/config.py

@@ -0,0 +1,172 @@
+"""
+Configuration loader for viz-platform MCP Server.
+
+Implements hybrid configuration system:
+- System-level: ~/.config/claude/viz-platform.env (theme preferences)
+- Project-level: .env (DMC version overrides)
+- Auto-detection: DMC package version from installed package
+"""
+from pathlib import Path
+from dotenv import load_dotenv
+import os
+import logging
+from typing import Dict, Optional
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+
+class VizPlatformConfig:
+    """Hybrid configuration loader for viz-platform tools"""
+
+    def __init__(self):
+        self.dmc_version: Optional[str] = None
+        self.theme_dir_user: Path = Path.home() / '.config' / 'claude' / 'themes'
+        self.theme_dir_project: Optional[Path] = None
+        self.default_theme: Optional[str] = None
+
+    def load(self) -> Dict[str, any]:
+        """
+        Load configuration from system and project levels.
+
+        Returns:
+            Dict containing dmc_version, theme directories, and availability flags
+        """
+        # Load system config
+        system_config = Path.home() / '.config' / 'claude' / 'viz-platform.env'
+        if system_config.exists():
+            load_dotenv(system_config)
+            logger.info(f"Loaded system configuration from {system_config}")
+
+        # Find project directory
+        project_dir = self._find_project_directory()
+
+        # Load project config (overrides system)
+        if project_dir:
+            project_config = project_dir / '.env'
+            if project_config.exists():
+                load_dotenv(project_config, override=True)
+                logger.info(f"Loaded project configuration from {project_config}")
+
+            # Set project theme directory
+            self.theme_dir_project = project_dir / '.viz-platform' / 'themes'
+
+        # Get DMC version (from env or auto-detect)
+        self.dmc_version = os.getenv('DMC_VERSION') or self._detect_dmc_version()
+        self.default_theme = os.getenv('VIZ_DEFAULT_THEME')
+
+        # Ensure user theme directory exists
+        self.theme_dir_user.mkdir(parents=True, exist_ok=True)
+
+        return {
+            'dmc_version': self.dmc_version,
+            'dmc_available': self.dmc_version is not None,
+            'theme_dir_user': str(self.theme_dir_user),
+            'theme_dir_project': str(self.theme_dir_project) if self.theme_dir_project else None,
+            'default_theme': self.default_theme,
+            'project_dir': str(project_dir) if project_dir else None
+        }
+
+    def _detect_dmc_version(self) -> Optional[str]:
+        """
+        Auto-detect installed Dash Mantine Components version.
+
+        Returns:
+            Version string (e.g., "0.14.7") or None if not installed
+        """
+        try:
+            from importlib.metadata import version
+            dmc_version = version('dash-mantine-components')
+            logger.info(f"Detected DMC version: {dmc_version}")
+            return dmc_version
+        except ImportError:
+            logger.warning("dash-mantine-components not installed - using registry fallback")
+            return None
+        except Exception as e:
+            logger.warning(f"Could not detect DMC version: {e}")
+            return None
+
+    def _find_project_directory(self) -> Optional[Path]:
+        """
+        Find the user's project directory.
+
+        Returns:
+            Path to project directory, or None if not found
+        """
+        # Strategy 1: Check CLAUDE_PROJECT_DIR environment variable
+        project_dir = os.getenv('CLAUDE_PROJECT_DIR')
+        if project_dir:
+            path = Path(project_dir)
+            if path.exists():
+                logger.info(f"Found project directory from CLAUDE_PROJECT_DIR: {path}")
+                return path
+
+        # Strategy 2: Check PWD
+        pwd = os.getenv('PWD')
+        if pwd:
+            path = Path(pwd)
+            if path.exists() and (
+                (path / '.git').exists() or
+                (path / '.env').exists() or
+                (path / '.viz-platform').exists()
+            ):
+                logger.info(f"Found project directory from PWD: {path}")
+                return path
+
+        # Strategy 3: Check current working directory
+        cwd = Path.cwd()
+        if (cwd / '.git').exists() or (cwd / '.env').exists() or (cwd / '.viz-platform').exists():
+            logger.info(f"Found project directory from cwd: {cwd}")
+            return cwd
+
+        logger.debug("Could not determine project directory")
+        return None
+
+
+def load_config() -> Dict[str, any]:
+    """
+    Convenience function to load configuration.
+
+    Returns:
+        Configuration dictionary
+    """
+    config = VizPlatformConfig()
+    return config.load()
+
+
+def check_dmc_version() -> Dict[str, any]:
+    """
+    Check DMC installation status for SessionStart hook.
+
+    Returns:
+        Dict with installation status and version info
+    """
+    config = load_config()
+
+    if not config.get('dmc_available'):
+        return {
+            'installed': False,
+            'message': 'dash-mantine-components not installed. Run: pip install dash-mantine-components'
+        }
+
+    version = config.get('dmc_version', 'unknown')
+
+    # Check for registry compatibility
+    registry_path = Path(__file__).parent.parent / 'registry'
+    major_minor = '.'.join(version.split('.')[:2]) if version else None
+    registry_file = registry_path / f'dmc_{major_minor.replace(".", "_")}.json' if major_minor else None
+
+    if registry_file and registry_file.exists():
+        return {
+            'installed': True,
+            'version': version,
+            'registry_available': True,
+            'message': f'DMC {version} ready with component registry'
+        }
+    else:
+        return {
+            'installed': True,
+            'version': version,
+            'registry_available': False,
+            'message': f'DMC {version} installed but no matching registry. Validation may be limited.'
+        }