feat: V2 microservices stack — backend services, gateway, JWT auth

Add full V2 architecture: identity, content, studio (.NET 10) and file,
render, notification, gateway (Go) services with vendored deps, plus DB
migrations, event/API contracts, and an init-db script.

Wire the Next.js frontend to the gateway: server-side JWT auth routes
(login/register/refresh/logout/me), gateway fetch helper, and session/
cookie/jwt helpers under src/lib.

Containerize the stack via docker-compose.v2.yml and per-service
Dockerfiles. Base images resolve through a Nexus mirror (Docker Hub) and
MCR directly; npm/NuGet pull from Nexus groups. Self-host fonts via
next/font/local to avoid Google Fonts (geo-blocked).

Add CI workflow and ignore .env.v2, *.stackdump, and .NET bin/obj.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

services/content/FlatRender.ContentSvc/Infrastructure/Data/PreserveCaseNameTranslator.cs

@@ -0,0 +1,18 @@
+using Npgsql;
+
+namespace FlatRender.ContentSvc.Infrastructure.Data;
+
+/// <summary>
+/// Npgsql name translator that returns CLR names verbatim. The database enum labels
+/// match the C# enum member names exactly (e.g. 'FIX', 'MockUp', 'fill', 'LEFT_JUSTIFY'),
+/// so no snake_case translation may be applied to enum values. PG type names are passed
+/// explicitly wherever this translator is used, so type-name translation is moot.
+/// </summary>
+public sealed class PreserveCaseNameTranslator : INpgsqlNameTranslator
+{
+    public static readonly PreserveCaseNameTranslator Instance = new();
+
+    public string TranslateTypeName(string clrName) => clrName;
+
+    public string TranslateMemberName(string clrName) => clrName;
+}