Add passkey prompt dismissal and consolidate company admin navigation

- Add "Don't ask me again" to passkey enrollment prompt (PasskeyPromptDismissed
  field on ApplicationUser; DismissPrompt POST action; migration applied)
- Add Subscription & Features button to Companies/Index btn-group and
  Companies/Edit header for direct navigation to SubscriptionManagement/Manage
- Add Edit Company back-link on SubscriptionManagement/Manage
- Remove duplicate AI Features section from Companies/Edit (managed exclusively
  via Subscription & Features page)

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

src/PowderCoating.Core/Entities/ApplicationUser.cs

@@ -61,6 +61,9 @@ public class ApplicationUser : IdentityUser
     public DateTime? UpdatedAt { get; set; }
     public DateTime? LastLoginDate { get; set; }
 
+    // Passkey enrollment prompt
+    public bool PasskeyPromptDismissed { get; set; } = false;
+
     // Ban
     public bool IsBanned { get; set; } = false;
     public DateTime? BannedAt { get; set; }