fix(config): enforce canonical receipt origin

[veryCrunchy]

What changed

• restore the canonical production public URL and production mode in the container and Compose defaults
• reject unsafe production receipt origins at startup
• keep the localhost fallback limited to development
• verify initial, idempotent retry, and reconciled receipts use the configured canonical origin
• clarify local and production configuration in the maintained documentation

Why

A successful intake can still be rejected by the client when the service builds receipt capability URLs from a localhost fallback. The client is correct to reject those URLs. This change fixes the server configuration boundary instead of weakening same-origin capability validation.

Validation

On the dedicated build host with Go 1.24 in Podman:

go test ./...
go build ./...
podman build --network host -t obiente-support-receipt-origin-hotfix:validation .

All Go packages passed, the backend and Vue frontend built, and the production container image completed successfully.