Simplify authentication to require URL and API key only

Major configuration and tooling updates:

Authentication Changes:
- Remove username/password authentication support
- Require PORTAINER_URL and PORTAINER_API_KEY (both mandatory)
- Simplify PortainerConfig class and validation logic
- Update all documentation to reflect API key requirement

Multiple Runtime Support:
- Add uvx support for running without installation
- Add uv support with dedicated wrapper script
- Add npx support with Node.js wrapper script
- Maintain backward compatibility with direct Python execution

Documentation Updates:
- Comprehensive README.md with all execution methods
- Detailed USAGE.md with step-by-step instructions
- Updated .env.example with clear required vs optional sections
- Enhanced docstrings in server.py and config.py

Tooling Support:
- package.json for npm/npx support with cross-platform wrapper
- scripts/run-with-uv.py for uv integration
- bin/portainer-core-mcp Node.js wrapper for npx
- test_uvx.py for uvx functionality testing

Configuration Improvements:
- Clear separation of required vs optional environment variables
- Better validation error messages
- Simplified authentication flow
- Enhanced project metadata in pyproject.toml

🤖 Generated with [Claude Code](https://claude.ai/code)

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

scripts/run-with-uv.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+"""
+UV runner script for Portainer Core MCP Server.
+
+This script provides a way to run the MCP server using uv for dependency management.
+"""
+
+import os
+import sys
+import subprocess
+from pathlib import Path
+
+
+def find_project_root():
+    """Find the project root directory."""
+    current = Path(__file__).parent
+    while current != current.parent:
+        if (current / "pyproject.toml").exists():
+            return current
+        current = current.parent
+    return Path(__file__).parent.parent
+
+
+def check_uv():
+    """Check if uv is installed."""
+    try:
+        subprocess.run(["uv", "--version"], capture_output=True, check=True)
+        return True
+    except (subprocess.CalledProcessError, FileNotFoundError):
+        return False
+
+
+def run_server():
+    """Run the server using uv."""
+    project_root = find_project_root()
+    
+    # Check if uv is available
+    if not check_uv():
+        print("❌ uv is not installed or not in PATH")
+        print("💡 Install uv: pip install uv")
+        print("💡 Or use: python run_server.py")
+        sys.exit(1)
+    
+    print("🚀 Starting Portainer Core MCP Server with uv...")
+    
+    # Change to project root
+    os.chdir(project_root)
+    
+    # Run the server with uv
+    try:
+        subprocess.run([
+            "uv", "run", 
+            "python", "run_server.py"
+        ], check=True)
+    except subprocess.CalledProcessError as e:
+        print(f"❌ Server failed with exit code {e.returncode}")
+        sys.exit(e.returncode)
+    except KeyboardInterrupt:
+        print("\n👋 Server stopped by user")
+        sys.exit(0)
+
+
+if __name__ == "__main__":
+    run_server()