feat(backend): Create Sprint 2 backend Stories and Tasks

Created detailed implementation plans for Sprint 2 backend work:

Story 1: Audit Log Foundation (Phase 1)
- Task 1: Design AuditLog database schema and create migration
- Task 2: Create AuditLog entity and Repository
- Task 3: Implement EF Core SaveChangesInterceptor
- Task 4: Write unit tests for audit logging
- Task 5: Integrate with ProjectManagement Module

Story 2: Audit Log Core Features (Phase 2)
- Task 1: Implement Changed Fields Detection (JSON Diff)
- Task 2: Integrate User Context Tracking
- Task 3: Add Multi-Tenant Isolation
- Task 4: Implement Audit Query API
- Task 5: Write Integration Tests

Story 3: Sprint Management Module
- Task 1: Create Sprint Aggregate Root and Domain Events
- Task 2: Implement Sprint Repository and EF Core Configuration
- Task 3: Create CQRS Commands and Queries
- Task 4: Implement Burndown Chart Calculation
- Task 5: Add SignalR Real-Time Notifications
- Task 6: Write Integration Tests

Total: 3 Stories, 16 Tasks, 24 Story Points (8+8+8)
Estimated Duration: 10-12 days

All tasks include:
- Detailed technical implementation guidance
- Code examples and file paths
- Testing requirements (>= 90% coverage)
- Performance benchmarks (< 5ms audit overhead)
- Multi-tenant security validation

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

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

docs/plans/sprint_2_story_1_task_2.md

@@ -0,0 +1,122 @@
+---
+task_id: sprint_2_story_1_task_2
+story: sprint_2_story_1
+status: not_started
+estimated_hours: 4
+created_date: 2025-11-05
+assignee: Backend Team
+---
+
+# Task 2: Create AuditLog Entity and Repository
+
+**Story**: Story 1 - Audit Log Foundation (Phase 1)
+**Estimated**: 4 hours
+
+## Description
+
+Create the AuditLog domain entity and repository pattern implementation to support CRUD operations and querying audit logs with proper multi-tenant isolation.
+
+## Acceptance Criteria
+
+- [ ] AuditLog entity created in Domain layer
+- [ ] IAuditLogRepository interface defined
+- [ ] AuditLogRepository implementation with EF Core
+- [ ] Multi-tenant query filtering applied
+- [ ] Unit tests for repository methods
+
+## Implementation Details
+
+**Files to Create**:
+
+1. **Domain Entity**: `colaflow-api/src/ColaFlow.Domain/Entities/AuditLog.cs`
+```csharp
+public class AuditLog
+{
+    public Guid Id { get; set; }
+    public Guid TenantId { get; set; }
+    public string EntityType { get; set; } = string.Empty;
+    public Guid EntityId { get; set; }
+    public AuditAction Action { get; set; } // Enum: Create, Update, Delete
+    public Guid? UserId { get; set; }
+    public DateTime Timestamp { get; set; }
+    public string? OldValues { get; set; } // JSONB stored as string
+    public string? NewValues { get; set; } // JSONB stored as string
+}
+
+public enum AuditAction
+{
+    Create,
+    Update,
+    Delete
+}
+```
+
+2. **Repository Interface**: `colaflow-api/src/ColaFlow.Domain/Repositories/IAuditLogRepository.cs`
+```csharp
+public interface IAuditLogRepository
+{
+    Task<AuditLog?> GetByIdAsync(Guid id);
+    Task<List<AuditLog>> GetByEntityAsync(string entityType, Guid entityId);
+    Task AddAsync(AuditLog auditLog);
+    Task<int> SaveChangesAsync(CancellationToken cancellationToken = default);
+}
+```
+
+3. **Repository Implementation**: `colaflow-api/src/ColaFlow.Infrastructure/Repositories/AuditLogRepository.cs`
+```csharp
+public class AuditLogRepository : IAuditLogRepository
+{
+    private readonly ColaFlowDbContext _context;
+    private readonly ITenantContext _tenantContext;
+
+    public AuditLogRepository(ColaFlowDbContext context, ITenantContext tenantContext)
+    {
+        _context = context;
+        _tenantContext = tenantContext;
+    }
+
+    public async Task<List<AuditLog>> GetByEntityAsync(string entityType, Guid entityId)
+    {
+        var tenantId = _tenantContext.TenantId;
+        return await _context.AuditLogs
+            .Where(a => a.TenantId == tenantId && a.EntityType == entityType && a.EntityId == entityId)
+            .OrderByDescending(a => a.Timestamp)
+            .ToListAsync();
+    }
+
+    // ... other methods
+}
+```
+
+4. **EF Core Configuration**: `colaflow-api/src/ColaFlow.Infrastructure/Data/Configurations/AuditLogConfiguration.cs`
+```csharp
+public class AuditLogConfiguration : IEntityTypeConfiguration<AuditLog>
+{
+    public void Configure(EntityTypeBuilder<AuditLog> builder)
+    {
+        builder.ToTable("AuditLogs");
+        builder.HasKey(a => a.Id);
+
+        builder.Property(a => a.EntityType).IsRequired().HasMaxLength(100);
+        builder.Property(a => a.Action).IsRequired();
+        builder.Property(a => a.Timestamp).IsRequired();
+
+        // JSONB columns
+        builder.Property(a => a.OldValues).HasColumnType("jsonb");
+        builder.Property(a => a.NewValues).HasColumnType("jsonb");
+
+        // Multi-tenant global query filter
+        builder.HasQueryFilter(a => a.TenantId == Guid.Empty); // Will be replaced by TenantContext
+    }
+}
+```
+
+## Testing
+
+- Unit tests for repository methods
+- Verify multi-tenant filtering works
+- Test JSONB serialization/deserialization
+
+---
+
+**Created**: 2025-11-05 by Backend Agent