Reorganise by feature, rename to Novelly, add Aspire and a pre-push hook

The layered split into Domain/Application/Infrastructure/Api was forcing
organisation by layer: adding one capability meant touching four projects and
four folders that each held a slice of it. Those four projects are now one
feature-organised Novelly.Api, where each folder — Projects, Characters,
Chapters, Beats, Scenes, Tags, Agent — holds its entity, DTOs, service and
endpoints together. Common/ holds what genuinely crosses features (the patch
semantics, the two exception types, DraftStatus) and Data/ holds the DbContext
and migrations.

Six .NET projects become five: the three layer projects are gone, and
Novelly.AppHost and Novelly.ServiceDefaults are new.

- Namespaces move from NovelSoftware.* to Novelly.*, including the entity type
  names recorded in the EF model snapshots. The migration ids are untouched, so
  an existing novel.db still migrates cleanly — verified against a fresh file.
- Aspire orchestration mirrors the mic-check setup: the AppHost starts the API
  on :5080 and the Vite dev server on :5173, and the API picks up OpenTelemetry,
  health checks and service discovery from ServiceDefaults. /health and /alive
  now answer in development.
- A Husky pre-push hook runs scripts/ci/prepush.sh: build, test, then a web
  build. The scripts are plain bash so CI can run the same steps.
- The MCP server's env var is now NOVELLY_API_URL.

Verified beyond the build: 44 tests pass, the web client builds, the API was
exercised over curl (project/chapter/beat/tag round trip, tag cross-reference,
503 on the agent without a key while conversation listing still returns 200),
the MCP server was driven over stdio JSON-RPC (26 tools, errors still surface
the API's own message rather than being flattened), and the AppHost was run to
confirm both resources come up and Vite proxies /api through to the API.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S56bfZMGe1hnhpWP4CjjNw

tests/Novelly.Api.Tests/ServiceTestFixture.cs

@@ -0,0 +1,50 @@
+using Novelly.Api.Beats;
+using Novelly.Api.Chapters;
+using Novelly.Api.Characters;
+using Novelly.Api.Projects;
+using Novelly.Api.Scenes;
+using Novelly.Api.Tags;
+
+namespace Novelly.Api.Tests;
+
+/// <summary>
+/// Shared plumbing for the service tests: a fresh in-memory database and a matching set
+/// of services per test.
+/// </summary>
+/// <remarks>
+/// The setup lives in <c>[SetUp]</c> rather than a constructor or field initialisers
+/// because NUnit builds one fixture instance for the whole class — anything created once
+/// would leak state from one test into the next.
+/// </remarks>
+public abstract class ServiceTestFixture
+{
+    protected TestDatabase Db { get; private set; } = null!;
+    protected TagService Tags { get; private set; } = null!;
+    protected ProjectService Projects { get; private set; } = null!;
+    protected CharacterService Characters { get; private set; } = null!;
+    protected ChapterService Chapters { get; private set; } = null!;
+    protected SceneService Scenes { get; private set; } = null!;
+    protected BeatService Beats { get; private set; } = null!;
+
+    [SetUp]
+    public void SetUpFixture()
+    {
+        Db = new TestDatabase();
+        Tags = new TagService(Db.Context);
+        Projects = new ProjectService(Db.Context);
+        Characters = new CharacterService(Db.Context, Tags);
+        Chapters = new ChapterService(Db.Context, Tags);
+        Scenes = new SceneService(Db.Context);
+        Beats = new BeatService(Db.Context, Tags);
+
+        OnSetUp();
+    }
+
+    /// <summary>Runs after the services exist, for per-class seed data.</summary>
+    protected virtual void OnSetUp()
+    {
+    }
+
+    [TearDown]
+    public void TearDownFixture() => Db.Dispose();
+}