Add Timeclock settings tab in Company Settings with multi-kiosk support

Settings tab (Company Settings > Timeclock):
- Enable/disable timeclock toggle (hides nav link and attendance report when off)
- Allow multiple clock-ins per day toggle
- Auto clock-out after X hours (auto-closes forgotten open entries on next punch)
- Kiosk devices table: lists activated tablets with name, activated date, last seen;
  Deactivate button removes that device's access immediately

Multi-kiosk support (replaces single TimeclockKioskToken on Company):
- New TimeclockKioskDevice entity (one row per tablet, unique token, DeviceName, LastSeenAt)
- KioskActivate GET shows a form for optional device name before activating
- KioskDeactivate POST accepts device ID, deletes specific row (not all devices)
- Kiosk validation (Kiosk, KioskEmployees, KioskPunch) queries device table with
  ignoreQueryFilters since no user is logged in on kiosk requests
- LastSeenAt updated on each Kiosk page load

Enforcement:
- ClockIn and KioskPunch both auto-close stale entries if AutoClockOutHours is set
- ClockIn and KioskPunch both block second same-day punch if AllowMultiplePunches=false
- TimeclockEnabled=false hides nav link (SubscriptionMiddleware sets Items key) and
  returns Forbid on kiosk punch
- Migration: AddTimeclockSettings (adds 3 columns to Companies, new TimeclockKioskDevices table)

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

src/PowderCoating.Web/Views/Shared/_Layout.cshtml

@@ -1270,10 +1270,13 @@ var hasReports = _isAdminOrManager || User.HasClaim("Permission", "ViewReports")
                         <span>Maintenance</span>
                     </a>
                 }
+                @if (Context.Items["TimeclockEnabled"] as bool? == true)
+                {
                 <a asp-controller="Timeclock" asp-action="Index" class="nav-link" data-nav="ops">
                     <i class="bi bi-clock-history"></i>
                     <span>Timeclock</span>
                 </a>
+                }
 
                 @* ── Reports & Templates ──────────────────────────────────── *@
                 @if (hasReports || hasJobs)