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.Web/vite.config.ts

@@ -6,8 +6,6 @@ export default defineConfig({
   plugins: [react(), tailwindcss()],
   server: {
     port: 5173,
-    // Proxy the API in dev so the browser sees a single origin and CORS never enters
-    // the picture during local development.
     proxy: {
       '/api': {
         target: process.env.VITE_API_URL ?? 'http://localhost:5080',