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.

tests/Novelly.Api.Tests/OpenQuestionTests.cs

@@ -182,7 +182,7 @@ public class OpenQuestionTests : ServiceTestFixture
     }
 
     [Test]
-    public async Task Deleting_a_chapter_leaves_its_questions_open_rather_than_taking_them()
+    public async Task Trashing_a_chapter_leaves_its_questions_open_and_pinned_but_hides_the_chapter()
     {
         var question = await Questions.CreateAsync(_novelId, new CreateOpenQuestionRequest(
             "Does she know about the letter?", ChapterId: _chapterId));
@@ -190,10 +190,12 @@ public class OpenQuestionTests : ServiceTestFixture
         await Chapters.DeleteAsync(_chapterId);
 
         var survivor = (await Questions.GetAsync(question.Id))!;
+        var response = survivor.ToResponse();
 
         Assert.Multiple(() =>
         {
-            Assert.That(survivor.ChapterId, Is.Null);
+            Assert.That(survivor.ChapterId, Is.EqualTo(_chapterId), "the pin survives so restoring the chapter restores the link");
+            Assert.That(response.ChapterTitle, Is.Null);
             Assert.That(survivor.Question, Is.EqualTo("Does she know about the letter?"));
         });
     }