Add Serilog console logging across the API

Information at endpoint and service-method boundaries, Debug in deeper
helpers, Warning before expected/recoverable failures (not-found,
validation, agent tool errors), Error on caught exceptions. Serilog
wraps the exception handler so request-completion logs report the
resolved status code rather than the raw exception. Never logs prose
bodies or the Anthropic API key.

src/Novelly.Api/Projects/ProjectEndpoints.cs

@@ -1,10 +1,12 @@
+using Novelly.Api.Common;
+
 namespace Novelly.Api.Projects;
 
 public static class ProjectEndpoints
 {
     public static IEndpointRouteBuilder MapProjectEndpoints(this IEndpointRouteBuilder app)
     {
-        var group = app.MapGroup("/api/projects").WithTags("Projects");
+        var group = app.MapGroup("/api/projects").WithTags("Projects").AddEndpointFilter<RequestLoggingEndpointFilter>();
 
         group.MapGet("/", async (ProjectService service, CancellationToken ct) =>
                 Results.Ok(await service.ListAsync(ct)))