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/Beats/Beat.cs

@@ -37,6 +37,7 @@ public class BeatEntityTypeConfiguration : IEntityTypeConfiguration<Beat>
     {
         entity.Property(b => b.Title).IsRequired().HasMaxLength(200);
         entity.HasIndex(b => new { b.ChapterId, b.SortOrder });
+        entity.HasQueryFilter(b => b.Chapter!.DeletedAt == null);
 
         entity.HasOne(b => b.Chapter).WithMany(c => c.Beats)
             .HasForeignKey(b => b.ChapterId).OnDelete(DeleteBehavior.Cascade);