Add optional SSO env vars to Docker Compose

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Motivation

• Allow users to enable/configure additional SSO providers solely via the env file without editing the compose file.

Description

• Add GitHub, GitLab, Keycloak and Okta environment mappings to the rtap-web service in deploy/docker/docker-compose.yml (GITHUB_CLIENT_ID, GITHUB_CLIENT_SECRET, GITLAB_CLIENT_ID, GITLAB_CLIENT_SECRET, KEYCLOAK_CLIENT_ID, KEYCLOAK_CLIENT_SECRET, KEYCLOAK_ISSUER, OKTA_CLIENT_ID, OKTA_CLIENT_SECRET, OKTA_ISSUER).

Testing

• No automated tests were run for this change (no npm run check or npm run test executed).

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Codex Task