feat(backend)!: Method to save provider agreements

[AntonioVentilii]

Motivation

To persist the acknowledgment of terms and agreements of providers by our suers, we need some methods to update the provider agreements of a user's profile.

BREAKING CHANGE: new method to update the provider agreements.

[Copilot]

Pull request overview

Adds a new backend update method to persist per-provider agreement acknowledgements (with audit history), alongside the necessary Candid/TypeScript declaration updates and integration tests.

Changes:

• Introduces update_provider_agreements update call and request type, wiring it through the user profile API/service layer.
• Extends StoredUserProfile update logic to merge provider agreements into the stored profile state.
• Adds integration tests covering provider agreement updates, version mismatch, validation, coexistence with internal agreements, and history recording.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/shared/src/impls.rs	Adjusts provider-agreement update API on StoredUserProfile to accept an owned map.
src/backend/src/user_profile/service.rs	Implements service-layer handler and history entry collection for provider agreements.
src/backend/src/api/user_profile.rs	Exposes update_provider_agreements as a canister update method.
src/backend/src/lib.rs	Wires new request/response types into the backend crate exports/imports.
src/backend/backend.did	Adds UpdateProviderAgreementsRequest type and update_provider_agreements service method.
src/declarations/backend/backend.factory.did.js	Updates generated JS IDL factory with the new request type and method.
src/declarations/backend/backend.factory.certified.did.js	Updates generated certified JS IDL factory with the new request type and method.
src/declarations/backend/backend.did.d.ts	Updates generated TS declarations with the new request type and method docs.
src/backend/tests/it/agreements.rs	Adds integration tests for provider agreements behavior and audit history.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.