fix(self-hosted): proxy .well-known route for auth (#50306)

docker/volumes/proxy/caddy/Caddyfile

@@ -1,5 +1,5 @@
 {$PROXY_DOMAIN} {
-    @supabase_api path /auth/v1/* /rest/v1/* /graphql/v1 /realtime/v1/* /storage/v1/* /functions/v1/* /mcp /sso/*
+    @supabase_api path /auth/v1/* /rest/v1/* /graphql/v1 /realtime/v1/* /storage/v1/* /functions/v1/* /mcp /sso/* /.well-known/oauth-authorization-server
 
     handle @supabase_api {
         reverse_proxy api-gw:8000

docker/volumes/proxy/nginx/supabase-nginx.conf.tpl

@@ -92,4 +92,8 @@ server {
     location /sso {
         proxy_pass http://api_gw_upstream;
     }
+
+    location = /.well-known/oauth-authorization-server {
+        proxy_pass http://api_gw_upstream;
+    }
 }