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/Services/ResourceDiscoveryServiceTests.cs

@@ -0,0 +1,72 @@
+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.Services;
+
+public class ResourceDiscoveryServiceTests
+{
+    private readonly IResourceDiscoveryService _discoveryService;
+    private readonly ILogger<ResourceDiscoveryService> _mockLogger;
+
+    public ResourceDiscoveryServiceTests()
+    {
+        _mockLogger = Substitute.For<ILogger<ResourceDiscoveryService>>();
+        _discoveryService = new ResourceDiscoveryService(_mockLogger);
+    }
+
+    [Fact]
+    public void DiscoverResourceTypes_ShouldFindAllResourceImplementations()
+    {
+        // Act
+        var resourceTypes = _discoveryService.DiscoverResourceTypes();
+
+        // Assert
+        resourceTypes.Should().NotBeEmpty();
+        resourceTypes.Should().AllSatisfy(type =>
+        {
+            typeof(IMcpResource).IsAssignableFrom(type).Should().BeTrue();
+            type.IsInterface.Should().BeFalse();
+            type.IsAbstract.Should().BeFalse();
+        });
+    }
+
+    [Fact]
+    public void DiscoverResourceTypes_ShouldFindKnownResources()
+    {
+        // Act
+        var resourceTypes = _discoveryService.DiscoverResourceTypes();
+
+        // Assert - should find at least these known resources
+        var typeNames = resourceTypes.Select(t => t.Name).ToList();
+        typeNames.Should().Contain("ProjectsListResource");
+        typeNames.Should().Contain("ProjectsGetResource");
+        typeNames.Should().Contain("IssuesSearchResource");
+        typeNames.Should().Contain("IssuesGetResource");
+        typeNames.Should().Contain("SprintsCurrentResource");
+        typeNames.Should().Contain("UsersListResource");
+    }
+
+    [Fact]
+    public void DiscoverResourceTypes_ShouldNotIncludeInterfaces()
+    {
+        // Act
+        var resourceTypes = _discoveryService.DiscoverResourceTypes();
+
+        // Assert
+        resourceTypes.Should().NotContain(t => t.IsInterface);
+    }
+
+    [Fact]
+    public void DiscoverResourceTypes_ShouldNotIncludeAbstractClasses()
+    {
+        // Act
+        var resourceTypes = _discoveryService.DiscoverResourceTypes();
+
+        // Assert
+        resourceTypes.Should().NotContain(t => t.IsAbstract);
+    }
+}