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

src/Novelly.Api/Common/AgentNotConfiguredException.cs

@@ -0,0 +1,8 @@
+namespace Novelly.Api.Common;
+
+/// <summary>
+/// Thrown when the agent is asked to run but has no model credentials. This is a
+/// deployment problem rather than a bad request, so the API reports it as 503 — the rest
+/// of the app works fine without a key.
+/// </summary>
+public class AgentNotConfiguredException(string message) : Exception(message);

src/Novelly.Api/Common/DraftStatus.cs

@@ -0,0 +1,11 @@
+namespace Novelly.Api.Common;
+
+/// <summary>How far along a chapter or scene is in the drafting pipeline.</summary>
+public enum DraftStatus
+{
+    Planned,
+    Outlined,
+    Drafted,
+    Revised,
+    Final
+}

src/Novelly.Api/Common/NotFoundException.cs

@@ -0,0 +1,12 @@
+namespace Novelly.Api.Common;
+
+/// <summary>
+/// Thrown when a service is asked for an entity that does not exist. The API translates
+/// this into a 404 so services never have to know about HTTP.
+/// </summary>
+public class NotFoundException(string entity, Guid id)
+    : Exception($"{entity} '{id}' was not found.")
+{
+    public string Entity { get; } = entity;
+    public Guid Id { get; } = id;
+}

src/Novelly.Api/Common/NovellyServiceRegistration.cs

@@ -0,0 +1,42 @@
+using Microsoft.EntityFrameworkCore;
+using Novelly.Api.Agent;
+using Novelly.Api.Beats;
+using Novelly.Api.Chapters;
+using Novelly.Api.Characters;
+using Novelly.Api.Data;
+using Novelly.Api.Projects;
+using Novelly.Api.Scenes;
+using Novelly.Api.Tags;
+
+namespace Novelly.Api.Common;
+
+/// <summary>
+/// Wires up every feature's services in one place. Endpoints, the embedded agent and the
+/// MCP server all resolve the same instances, so a capability added here is available to
+/// all three.
+/// </summary>
+public static class NovellyServiceRegistration
+{
+    public static IServiceCollection AddNovelly(this IServiceCollection services, IConfiguration configuration)
+    {
+        var connectionString = configuration.GetConnectionString("Novel")
+            ?? "Data Source=novel.db";
+
+        services.AddDbContext<NovelDbContext>(options => options.UseSqlite(connectionString));
+        services.AddScoped<INovelDbContext>(sp => sp.GetRequiredService<NovelDbContext>());
+
+        services.AddScoped<ProjectService>();
+        services.AddScoped<CharacterService>();
+        services.AddScoped<BeatService>();
+        services.AddScoped<TagService>();
+        services.AddScoped<ChapterService>();
+        services.AddScoped<SceneService>();
+        services.AddScoped<NovelAgentToolset>();
+        services.AddScoped<NovelAgentService>();
+
+        services.Configure<AgentOptions>(configuration.GetSection(AgentOptions.SectionName));
+        services.AddScoped<IAgentModelClient, AnthropicAgentModelClient>();
+
+        return services;
+    }
+}

src/Novelly.Api/Common/Patch.cs

@@ -0,0 +1,15 @@
+namespace Novelly.Api.Common;
+
+/// <summary>
+/// Patch semantics shared by every update endpoint: a null value leaves the field
+/// untouched, an empty string clears it.
+/// </summary>
+internal static class Patch
+{
+    public static string? Apply(string? current, string? incoming) => incoming switch
+    {
+        null => current,
+        "" => null,
+        _ => incoming
+    };
+}