Add Skill navigation to Phase/ProjectSection, refactor logic

- Add Skill navigation properties to PhaseSection and ProjectSection, with EF Core mappings and migration for foreign keys and indexes.
- Refactor SetSkillFlags in GetProjectsListQueryHandler for clarity and efficiency; use eager loading for Skill.
- Add HasRemainingTime() to TaskSection and enforce time check in ChangeStatusSectionCommandHandler.
- Optimize EmployeeDocumentsRepository queries; add EmployeeId to WorkshopWithEmployeeDocumentsViewModel.
- Improve CustomExceptionHandler to handle FluentValidation exceptions and return proper status codes.
- Add FluentValidation package reference and perform minor code cleanups.

ProgramManager/src/Domain/GozareshgirProgramManager.Domain/ProjectAgg/Entities/PhaseSection.cs

@@ -1,4 +1,5 @@
 using GozareshgirProgramManager.Domain._Common;
+using GozareshgirProgramManager.Domain.SkillAgg.Entities;
 
 namespace GozareshgirProgramManager.Domain.ProjectAgg.Entities;
 
@@ -22,6 +23,7 @@ public class PhaseSection : EntityBase<Guid>
 
     // Navigation property
     public ProjectPhase Phase { get; private set; } = null!;
+    public Skill? Skill { get; set; }
 
     public void UpdateUser(long userId)
     {

ProgramManager/src/Domain/GozareshgirProgramManager.Domain/ProjectAgg/Entities/ProjectSection.cs

@@ -1,4 +1,5 @@
 using GozareshgirProgramManager.Domain._Common;
+using GozareshgirProgramManager.Domain.SkillAgg.Entities;
 
 namespace GozareshgirProgramManager.Domain.ProjectAgg.Entities;
 
@@ -21,6 +22,7 @@ public class ProjectSection : EntityBase<Guid>
     public Guid SkillId { get; private set; }
 
     public Project Project { get; private set; } = null!;
+    public Skill? Skill { get; set; }
 
     public void UpdateUser(long userId)
     {

ProgramManager/src/Domain/GozareshgirProgramManager.Domain/ProjectAgg/Entities/TaskSection.cs

@@ -210,4 +210,11 @@ public class TaskSection : EntityBase<Guid>
     {
         _additionalTimes.Clear();
     }
+
+    public bool HasRemainingTime()
+    {
+        var totalSpent = GetTotalTimeSpent();
+        var finalEstimate = FinalEstimatedHours;
+        return totalSpent < finalEstimate;
+    }
 }