feat: Redmine SSO login + API key extraction working

Redmine SSO flow: Cloudron login -> click "Continue with KNEL Cloud"
button (#login-oauth-submit-1) -> authenticated. Required Cloudron
admin to grant vp-techops access to the Redmine app first.

API key was already present but hidden. Click "Show" in the
.api-key-actions section to reveal it from the #api-access-key
pre element. Key verified via X-Redmine-API-Key header.

docker-compose.yml

@@ -20,3 +20,4 @@ services:
       - ./dump-sso-flows.py:/app/dump-sso-flows.py:ro
       - ./provision-discourse.py:/app/provision-discourse.py:ro
       - ./provision-discourse-apikey.py:/app/provision-discourse-apikey.py:ro
+      - ./provision-redmine.py:/app/provision-redmine.py:ro