feat(backend): Implement Story 5.6 - Resource Registration & Discovery

Implemented pluggable resource registration and auto-discovery mechanism for MCP Resources.

Changes:
- Enhanced McpResourceDescriptor with metadata (Category, Version, Parameters, Examples, Tags, IsEnabled)
- Created ResourceDiscoveryService for Assembly scanning and auto-discovery
- Updated McpResourceRegistry with category support and grouping methods
- Enhanced ResourcesListMethodHandler to return categorized resources with full metadata
- Created ResourceHealthCheckHandler for resource availability verification
- Updated all existing Resources (Projects, Issues, Sprints, Users) with Categories and Versions
- Updated McpServiceExtensions to use auto-discovery at startup
- Added comprehensive unit tests for discovery and health check

Features:
✅ New Resources automatically discovered via Assembly scanning
✅ Resources organized by category (Projects, Issues, Sprints, Users)
✅ Rich metadata for documentation (parameters, examples, tags)
✅ Health check endpoint (resources/health) for monitoring
✅ Thread-safe registry operations

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

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

colaflow-api/tests/Modules/Mcp/ColaFlow.Modules.Mcp.Tests/Handlers/ResourceHealthCheckHandlerTests.cs

@@ -0,0 +1,94 @@
+using ColaFlow.Modules.Mcp.Application.Handlers;
+using ColaFlow.Modules.Mcp.Application.Services;
+using ColaFlow.Modules.Mcp.Contracts.Resources;
+using FluentAssertions;
+using Microsoft.Extensions.Logging;
+using NSubstitute;
+using Xunit;
+
+namespace ColaFlow.Modules.Mcp.Tests.Handlers;
+
+public class ResourceHealthCheckHandlerTests
+{
+    private readonly ILogger<ResourceHealthCheckHandler> _mockLogger;
+    private readonly IMcpResourceRegistry _mockRegistry;
+    private readonly ResourceHealthCheckHandler _handler;
+
+    public ResourceHealthCheckHandlerTests()
+    {
+        _mockLogger = Substitute.For<ILogger<ResourceHealthCheckHandler>>();
+        _mockRegistry = Substitute.For<IMcpResourceRegistry>();
+        _handler = new ResourceHealthCheckHandler(_mockLogger, _mockRegistry);
+    }
+
+    [Fact]
+    public void MethodName_ShouldBeResourcesHealth()
+    {
+        // Assert
+        _handler.MethodName.Should().Be("resources/health");
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithHealthyResources_ShouldReturnHealthyStatus()
+    {
+        // Arrange
+        var mockResource = Substitute.For<IMcpResource>();
+        mockResource.Uri.Returns("test://resource");
+        mockResource.Name.Returns("Test Resource");
+        mockResource.Category.Returns("Testing");
+        mockResource.GetDescriptor().Returns(new McpResourceDescriptor
+        {
+            Uri = "test://resource",
+            Name = "Test Resource",
+            Category = "Testing",
+            IsEnabled = true,
+            Version = "1.0"
+        });
+
+        _mockRegistry.GetAllResources()
+            .Returns(new List<IMcpResource> { mockResource }.AsReadOnly());
+
+        // Act
+        var result = await _handler.HandleAsync(null, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        var response = result as dynamic;
+        ((string)response.status).Should().Be("healthy");
+        ((int)response.totalResources).Should().Be(1);
+        ((int)response.healthyResources).Should().Be(1);
+        ((int)response.unhealthyResources).Should().Be(0);
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithUnhealthyResource_ShouldReturnDegradedStatus()
+    {
+        // Arrange
+        var mockResource = Substitute.For<IMcpResource>();
+        mockResource.Uri.Returns("test://resource");
+        mockResource.Name.Returns("Test Resource");
+        mockResource.Category.Returns("Testing");
+        mockResource.GetDescriptor().Returns(new McpResourceDescriptor
+        {
+            Uri = "",  // Invalid - empty URI
+            Name = "Test Resource",
+            Category = "Testing",
+            IsEnabled = true,
+            Version = "1.0"
+        });
+
+        _mockRegistry.GetAllResources()
+            .Returns(new List<IMcpResource> { mockResource }.AsReadOnly());
+
+        // Act
+        var result = await _handler.HandleAsync(null, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        var response = result as dynamic;
+        ((string)response.status).Should().Be("degraded");
+        ((int)response.totalResources).Should().Be(1);
+        ((int)response.healthyResources).Should().Be(0);
+        ((int)response.unhealthyResources).Should().Be(1);
+    }
+}