Add OIDC provider for Outline wiki SSO

Add oidc-provider with MongoDB adapter so ghostguild.org can act as
the identity provider for the self-hosted Outline wiki. Members
authenticate via the existing magic-link flow, with automatic SSO
when an active session exists. Includes interaction routes, well-known
discovery endpoint, and login page.

package.json

@@ -19,7 +19,7 @@
     "@nuxt/ui": "^4.0.0",
     "@nuxtjs/plausible": "^3.0.1",
     "@slack/web-api": "^7.10.0",
-"chrono-node": "^2.8.4",
+    "chrono-node": "^2.8.4",
     "cloudinary": "^2.7.0",
     "eslint": "^9.34.0",
     "isomorphic-dompurify": "^3.0.0",
@@ -28,6 +28,7 @@
     "mongoose": "^8.18.0",
     "nitro-cors": "^0.7.1",
     "nuxt": "^4.0.3",
+    "oidc-provider": "^9.6.1",
     "rate-limiter-flexible": "^9.1.1",
     "resend": "^6.0.1",
     "typescript": "^5.9.2",
@@ -38,6 +39,8 @@
   "devDependencies": {
     "@nuxt/test-utils": "^4.0.0",
     "@tailwindcss/typography": "^0.5.19",
+    "@types/jsonwebtoken": "^9.0.10",
+    "@types/oidc-provider": "^9.5.0",
     "jsdom": "^28.1.0",
     "vitest": "^4.0.18"
   }