Align client auth with external user server

[DmPrkp]

Summary

• point the Ionic auth model at a configurable user service with fallback endpoints and request options so it can talk to the external User server
• harden the auth store, base model, and settings page to normalize tokens/user payloads, custom header schemes, and optional profile data from the new service
• remove the NestJS auth module and migration from order-server so it no longer conflicts with the dedicated User server

Testing

• npm run build (ionic-client)

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Codex Task