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/render/vendor/github.com/goccy/go-json/.golangci.yml

@@ -0,0 +1,86 @@
+run:
+  skip-files:
+    - encode_optype.go
+    - ".*_test\\.go$"
+
+linters-settings:
+  govet:
+    enable-all: true
+    disable:
+      - shadow
+
+linters:
+  enable-all: true
+  disable:
+    - dogsled
+    - dupl
+    - exhaustive
+    - exhaustivestruct
+    - errorlint
+    - forbidigo
+    - funlen
+    - gci
+    - gochecknoglobals
+    - gochecknoinits
+    - gocognit
+    - gocritic
+    - gocyclo
+    - godot
+    - godox
+    - goerr113
+    - gofumpt
+    - gomnd
+    - gosec
+    - ifshort
+    - lll
+    - makezero
+    - nakedret
+    - nestif
+    - nlreturn
+    - paralleltest
+    - testpackage
+    - thelper
+    - wrapcheck
+    - interfacer
+    - lll
+    - nakedret
+    - nestif
+    - nlreturn
+    - testpackage
+    - wsl
+    - varnamelen
+    - nilnil
+    - ireturn
+    - govet
+    - forcetypeassert
+    - cyclop
+    - containedctx
+    - revive
+    - nosnakecase
+    - exhaustruct
+    - depguard
+
+issues:
+  exclude-rules:
+    # not needed
+    - path: /*.go
+      text: "ST1003: should not use underscores in package names"
+      linters:
+        - stylecheck
+    - path: /*.go
+      text: "don't use an underscore in package name"
+      linters:
+        - golint
+    - path: rtype.go
+      linters:
+        - golint
+        - stylecheck
+    - path: error.go
+      linters:
+        - staticcheck
+
+  # Maximum issues count per one linter. Set to 0 to disable. Default is 50.
+  max-issues-per-linter: 0
+
+  # Maximum count of issues with the same text. Set to 0 to disable. Default is 3.
+  max-same-issues: 0