feat(backend): Add ProjectManagement integration test infrastructure + fix API controller

Created comprehensive integration test infrastructure for ProjectManagement module:
- PMWebApplicationFactory with in-memory database support
- TestAuthHelper for JWT token generation
- Test project with all necessary dependencies

Fixed API Controller:
- Removed manual TenantId injection in ProjectsController
- TenantId now automatically extracted via ITenantContext in CommandHandler
- Maintained OwnerId extraction from JWT claims

Test Infrastructure:
- In-memory database for fast, isolated tests
- Support for multi-tenant scenarios
- JWT authentication helpers
- Cross-module database consistency

Next Steps:
- Write multi-tenant isolation tests (Phase 3.2)
- Write CRUD integration tests (Phase 3.3)

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

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

colaflow-api/src/ColaFlow.API/Controllers/ProjectsController.cs

@@ -57,14 +57,13 @@ public class ProjectsController(IMediator mediator) : ControllerBase
         [FromBody] CreateProjectCommand command,
         CancellationToken cancellationToken = default)
     {
-        // Extract TenantId and UserId from JWT claims
-        var tenantId = GetTenantIdFromClaims();
+        // Extract UserId from JWT claims
+        // Note: TenantId is now automatically extracted in the CommandHandler via ITenantContext
         var userId = GetUserIdFromClaims();
 
-        // Override command with authenticated user's context
+        // Override command with authenticated user's ID
         var commandWithContext = command with
         {
-            TenantId = tenantId,
             OwnerId = userId
         };
 
@@ -104,15 +103,7 @@ public class ProjectsController(IMediator mediator) : ControllerBase
         return NoContent();
     }
 
-    // Helper methods to extract claims
-    private Guid GetTenantIdFromClaims()
-    {
-        var tenantIdClaim = User.FindFirst("tenant_id")?.Value
-            ?? throw new UnauthorizedAccessException("Tenant ID not found in token");
-
-        return Guid.Parse(tenantIdClaim);
-    }
-
+    // Helper method to extract user ID from claims
     private Guid GetUserIdFromClaims()
     {
         var userIdClaim = User.FindFirst(ClaimTypes.NameIdentifier)?.Value