Feature/maintenance mode (#6930)

* Implement maintenance mode with Vercel Edge Config

* Error log is spam during development/ added \n in .env.example

* Exclude _next, /api for /maintenance page

* Re-instate previous config

* rtl: begone

* Added note to explain why /auth/login covers the maintenance page.

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Co-authored-by: Omar López <zomars@me.com>

.env.example

@@ -161,3 +161,6 @@ NEXT_PUBLIC_DISABLE_SIGNUP=
 
 # Content Security Policy
 CSP_POLICY=
+
+# Vercel Edge Config
+EDGE_CONFIG=