Add users, roles, and per-novel permissions

Introduces accounts (ASP.NET Identity + cookie auth), four global
roles (Admin/Writer/Editor/Reviewer), per-novel ownership and grants
via ProjectMember, and a service-API-key principal for the MCP server
and background import jobs. Enforcement lives in the application
services (not endpoint filters) so the embedded agent and MCP tools,
which call the same services directly, can't bypass it. Web client
gets a login page, session-aware routing, and a People section for
managing per-novel access.

Also includes prior in-flight changes from this branch (CLAUDE.md
compliance pass, dev-deploy docker-compose setup) that were
uncommitted when this feature work started.

src/Novelly.Api/Imports/ImportContracts.cs

@@ -13,7 +13,6 @@ public record ImportJobResponse(
     DateTimeOffset CreatedAt,
     DateTimeOffset UpdatedAt);
 
-/// <summary>Whether a source folder is ready for a fresh import, has one to resume, or is already done.</summary>
 public enum ImportReadiness
 {
     Fresh,
@@ -43,11 +42,6 @@ public class InspectImportRequestValidator : IModelValidator<InspectImportReques
     }
 }
 
-/// <summary>
-/// Starts a fresh import, resumes an incomplete one, or — with <see cref="ForceRestart"/> —
-/// deletes the ledger and the project it points at before starting clean. Resuming needs no
-/// flag: the importer always continues from the ledger it finds unless told to wipe it.
-/// </summary>
 public record StartImportRequest(string SourceRoot, bool ForceRestart = false);
 
 public class StartImportRequestValidator : IModelValidator<StartImportRequest>