Add soft delete + trash, keyboard-first web overhaul, move chapter tags to bottom

Adds SoftDelete/Trash across characters, chapters, locations, beats with a
purge schedule and Trash page. Reworks the web client for keyboard-driven
navigation (focus helpers, help overlay, keyboard.md doc). Moves the
ChapterPage tag editor to the bottom of the page to match CharacterDetailPage.

src/Novelly.Api/Characters/Character.cs

@@ -2,12 +2,13 @@ using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Metadata.Builders;
 using Novelly.Api.Beats;
 using Novelly.Api.Chapters;
+using Novelly.Api.Common;
 using Novelly.Api.Novels;
 using Novelly.Api.Tags;
 
 namespace Novelly.Api.Characters;
 
-public class Character
+public class Character : ISoftDeletable
 {
     public Guid Id { get; set; } = Guid.NewGuid();
     public Guid NovelId { get; set; }
@@ -46,6 +47,7 @@ public class Character
 
     public DateTimeOffset CreatedAt { get; set; } = DateTimeOffset.UtcNow;
     public DateTimeOffset UpdatedAt { get; set; } = DateTimeOffset.UtcNow;
+    public DateTimeOffset? DeletedAt { get; set; }
 
     public List<CharacterRelationship> Relationships { get; set; } = [];
     public List<Tag> Tags { get; set; } = [];
@@ -79,6 +81,7 @@ public class CharacterEntityTypeConfiguration : IEntityTypeConfiguration<Charact
         entity.Property(c => c.Importance).HasConversion<string>().HasMaxLength(32);
         entity.HasIndex(c => c.NovelId);
         entity.HasIndex(c => c.SameCharacterAsId);
+        entity.HasQueryFilter(c => c.DeletedAt == null);
 
         entity.HasMany(c => c.Relationships).WithOne(r => r.Character!)
             .HasForeignKey(r => r.CharacterId).OnDelete(DeleteBehavior.Cascade);
@@ -102,5 +105,7 @@ public class CharacterRelationshipEntityTypeConfiguration : IEntityTypeConfigura
 
         entity.HasOne(r => r.RelatedCharacter).WithMany()
             .HasForeignKey(r => r.RelatedCharacterId).OnDelete(DeleteBehavior.Restrict);
+
+        entity.HasQueryFilter(r => r.Character!.DeletedAt == null && r.RelatedCharacter!.DeletedAt == null);
     }
 }