Add Employee Timeclock feature with kiosk, attendance report, and payroll CSV export

- New EmployeeClockEntry entity (facility-level attendance, separate from job time entries)
- KioskPin added to ApplicationUser; TimeclockKioskToken added to Company
- TimeclockController: clock in/out, who's in, 14-day history, manager edit/delete,
  tablet kiosk with device-cookie auth, PIN management via Users edit page
- Kiosk UI: employee tile grid + 4-digit PIN pad + auto-detect clock-in vs clock-out
- Attendance report at /Reports/Attendance with weekly subtotal rows
- Payroll CSV export at /Reports/AttendanceCsv (flat, one row per segment)
- AllowCustomFormulas wired through PlatformSubscriptionController + subscription views
- Fix soft-delete bug on CustomItemTemplate (missing HasQueryFilter in OnModelCreating)
- Help article (Help/Timeclock.cshtml) and AI knowledge base updated
- Migrations: AddEmployeeTimeclock, AddTimeclockKioskToken

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Core/Entities/ApplicationUser.cs

@@ -73,6 +73,9 @@ public class ApplicationUser : IdentityUser
     // Passkey enrollment prompt
     public bool PasskeyPromptDismissed { get; set; } = false;
 
+    /// <summary>BCrypt hash of the employee's 4-digit kiosk PIN. Null means kiosk timeclock is disabled for this user.</summary>
+    public string? KioskPin { get; set; }
+
     // Ban
     public bool IsBanned { get; set; } = false;
     public DateTime? BannedAt { get; set; }