Enhance status display and entry details in HostsManagerApp

- Updated header title to "/etc/hosts Manager" and modified subtitle format.
- Implemented a dedicated overlay status bar for error messages, ensuring no layout shifts.
- Refactored entry details display to use DataTable with labeled rows for improved consistency.
- Added CSS styles for the new status bar and DataTable.
- Created tests for status bar visibility and DataTable functionality, ensuring all tests pass.

test_status_visibility.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+"""
+Test status bar visibility by triggering an error message manually.
+"""
+
+import asyncio
+from unittest.mock import patch, Mock
+from src.hosts.tui.app import HostsManagerApp
+
+async def test_status_bar_visibility():
+    """Test that the status bar becomes visible when an error occurs."""
+    print("Testing status bar visibility...")
+    
+    with patch('hosts.tui.app.HostsParser') as mock_parser_cls, \
+         patch('hosts.tui.app.Config') as mock_config_cls:
+        
+        # Set up mocks
+        mock_parser = Mock()
+        mock_config = Mock()
+        mock_parser_cls.return_value = mock_parser
+        mock_config_cls.return_value = mock_config
+        
+        # Create app
+        app = HostsManagerApp()
+        
+        # Mock the query_one method to capture status bar interactions
+        mock_status_bar = Mock()
+        original_query_one = app.query_one
+        
+        def mock_query_one(selector, widget_type=None):
+            if selector == "#status-bar":
+                return mock_status_bar
+            return original_query_one(selector, widget_type)
+        
+        app.query_one = mock_query_one
+        
+        # Test updating status with error message
+        print("🔧 Triggering error message...")
+        app.update_status("❌ Test error message")
+        
+        # Verify status bar operations
+        print("✅ Status bar operations:")
+        print(f"   - update() called: {mock_status_bar.update.called}")
+        print(f"   - remove_class('hidden') called: {mock_status_bar.remove_class.called}")
+        
+        if mock_status_bar.update.called:
+            call_args = mock_status_bar.update.call_args[0]
+            print(f"   - Message passed: '{call_args[0]}'")
+        
+        # Test clearing status
+        print("\n🔧 Clearing status message...")
+        app._clear_status_message()
+        
+        print("✅ Clear operations:")
+        print(f"   - update('') called: {mock_status_bar.update.call_count > 1}")
+        print(f"   - add_class('hidden') called: {mock_status_bar.add_class.called}")
+
+if __name__ == "__main__":
+    asyncio.run(test_status_bar_visibility())