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/notification/vendor/github.com/jackc/pgservicefile/README.md

@@ -0,0 +1,7 @@
+[![Go Reference](https://pkg.go.dev/badge/github.com/jackc/pgservicefile.svg)](https://pkg.go.dev/github.com/jackc/pgservicefile)
+[![Build Status](https://github.com/jackc/pgservicefile/actions/workflows/ci.yml/badge.svg)](https://github.com/jackc/pgservicefile/actions/workflows/ci.yml)
+
+
+# pgservicefile
+
+Package pgservicefile is a parser for PostgreSQL service files (e.g. `.pg_service.conf`).