feat(operator): scaffold apps/operator Nuxt app + multi-issuer JWT (O.3)

New Nuxt 3 app at apps/operator/ — internal admin portal on its own domain
(operator.dezky.local), own OAuth client (dezky-operator), own session
secrets, own cookies. Customer and operator surfaces can't decrypt each
other's session state.

OAuth flow verified end-to-end:
  - GET / → middleware redirect to /auth/login
  - User clicks Sign in → /auth/oidc/login → bounces to Authentik with
    client_id=dezky-operator, scope includes 'groups'
  - Authentik checks dezky-platform-admins group binding (added in O.1),
    silent-reauths via the existing auth.dezky.local session
  - Returns to /auth/oidc/callback with code, exchanges for token,
    creates session cookie on operator.dezky.local
  - Lands on pages/index.vue placeholder dashboard

Smoke test 'Create partner "test-partner"' button on the placeholder home
exercises the full operator-only authorization chain:
  - 1st call: 200, partner created in Mongo
  - 2nd call: 409 'already exists' (idempotency holds, token still valid)
  - Same call from the customer portal: 403 'requires operator-scoped
    token' (audience guard rejects dezky-portal aud)

JwtAuthGuard now multi-issuer in addition to multi-audience. Each
Authentik OAuth provider mints tokens with its own per-app iss URL
(.../application/o/<slug>/), so the guard accepts a comma-separated
AUTHENTIK_ISSUER. The audience-only fix from O.2 wasn't sufficient —
issuer is validated separately by jose.jwtVerify and was still pinned
to dezky-portal alone, yielding 'unexpected iss claim value' rejections.

Compose changes: new 'operator' service (Node 20 alpine, pnpm install +
nuxt dev, mkcert CA mount, traefik labels for operator.dezky.local +
TLS); new operator_node_modules volume; operator.dezky.local added to
traefik's Docker network aliases. Distinct OPERATOR_NUXT_OIDC_* session
secrets pulled from .env (gitignored, generated via openssl).

Real operator screens (sidebar, topbar, tenants, partners, etc.) come
in O.4. This commit is pure scaffolding + the security boundary proof.

apps/operator/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "@dezky/operator",
+  "version": "0.0.1",
+  "private": true,
+  "description": "Dezky operator portal — internal admin app (Nuxt 3)",
+  "scripts": {
+    "dev": "nuxt dev --host 0.0.0.0 --port 3000",
+    "build": "nuxt build",
+    "preview": "nuxt preview",
+    "typecheck": "nuxt typecheck",
+    "lint": "eslint ."
+  },
+  "dependencies": {
+    "nuxt": "^3.13.0",
+    "nuxt-oidc-auth": "1.0.0-beta.11",
+    "vue": "^3.5.0",
+    "vue-router": "^4.4.0"
+  },
+  "devDependencies": {
+    "@types/node": "^20.0.0",
+    "typescript": "^5.5.0"
+  },
+  "packageManager": "pnpm@9.12.0"
+}