Add CI workflow to verify Docker Compose file integrity

[Copilot]

All compose file combinations lacked automated validation, and several services declared in .env.example and referenced by overlay files were never defined, causing docker compose config to fail silently.

CI Workflow (.github/workflows/verify-compose.yml)

• Runs docker compose config --quiet on all 6 meaningful compose combinations on push/PR to compose or env files
• permissions: contents: read scoped per CodeQL best practice

Missing core services (compose.yaml)

Added qdrant, mongodb, infinity — present in .env.example and README's core infrastructure list but absent from the file. Each gets a named volume for persistence.

Missing app service (compose.apps.yaml)

Added openhands — image/port already in .env.example, security overlay already overrides it, but no base definition existed (causing docker compose config to error on the security combination).

Missing env vars (.env.example)

• COUCHDB_URL — derived URL, consistent with the other *_URL vars already present
• REDIS_PASSWORD — empty default (Redis ships with no auth); commented to clarify intent
• POSTGRES_DB, MYSQL_USER, MYSQL_PASSWORD, MYSQL_DATABASE — generic connection vars consumed by the agent security overlay's URL construction; commented to distinguish from the app-scoped variants