Support multiple allowed users for write access

MAPTOOL_ALLOWED_GITEA_USER now accepts a comma-separated list of
Gitea usernames instead of just one, for when more than one person
needs upload/delete/move access.

app.rb

@@ -24,13 +24,13 @@ module Maptool
 
     # Login delegates to the Gitea instance the user already has an account
     # on, rather than maintaining a local username/password — see
-    # docs/architecture.adoc. Only ALLOWED_GITEA_USER may write; anyone else
-    # can authenticate against Gitea but is still refused. No defaults for
-    # the OAuth2 client id/secret/user: blank values just mean login (and
-    # thus writing) doesn't work, which is fine outside production — nothing
-    # here is eagerly validated at load time.
+    # docs/architecture.adoc. Only users listed in ALLOWED_GITEA_USERS may
+    # write; anyone else can authenticate against Gitea but is still
+    # refused. No defaults for the OAuth2 client id/secret/user list: blank
+    # values just mean login (and thus writing) doesn't work, which is fine
+    # outside production — nothing here is eagerly validated at load time.
     GITEA_URL = ENV.fetch("GITEA_URL", "https://git.priesol.net")
-    ALLOWED_GITEA_USER = ENV.fetch("MAPTOOL_ALLOWED_GITEA_USER", "")
+    ALLOWED_GITEA_USERS = ENV.fetch("MAPTOOL_ALLOWED_GITEA_USER", "").split(",").map(&:strip)
     OAUTH_CLIENT = OAuth2::Client.new(
       ENV.fetch("GITEA_OAUTH_CLIENT_ID", ""),
       ENV.fetch("GITEA_OAUTH_CLIENT_SECRET", ""),
@@ -67,7 +67,7 @@ module Maptool
 
       token = OAUTH_CLIENT.auth_code.get_token(params[:code], redirect_uri: callback_url)
       user = token.get("/api/v1/user").parsed
-      halt 403, "not authorized" unless user["login"] == ALLOWED_GITEA_USER
+      halt 403, "not authorized" unless ALLOWED_GITEA_USERS.include?(user["login"])
 
       session[:user] = user["login"]
       redirect "/"