Strengthen UserRole contract tests beyond length/regex invariants

[marassteiner]

Context

Follow-up from review of #205 (feat(core): add the non-custodial wallet partner user role).

Finding

packages/core/src/__tests__/user-role.test.ts pins three invariants over Object.values(UserRole):

1. no duplicate values (user-role.test.ts:6-15)
2. anchored PascalCase /^[A-Z][A-Za-z]*$/ (user-role.test.ts:18-24)
3. fixed member count 13 (user-role.test.ts:26-28)

These do not pin the exact contract string for the new member in packages/core/src/definitions/jwt.ts:16:

NON_CUSTODIAL_WALLET_PARTNER = 'NonCustodialWalletPartner',

A typo such as 'NonCustodialWalletPartnr' would still satisfy uniqueness, regex, and length. The PR body intentionally rejected a tautological one-liner and preferred invariants — that is a valid design choice, not a merge-blocker for #205.

Separately, a fixed toHaveLength(13) fails on any parallel role addition (e.g. historical PARTNER work on other branches) and forces mechanical updates that do not improve contract safety on their own.

Evidence

• packages/core/src/__tests__/user-role.test.ts:6-28
• packages/core/src/definitions/jwt.ts:16
• PR: feat(core): add the non-custodial wallet partner user role #205

Suggested fix

Either:

• add an explicit pin for the new member:
  expect(UserRole.NON_CUSTODIAL_WALLET_PARTNER).toBe('NonCustodialWalletPartner')
  (and keep or drop the length check), or
• pin the full expected value list and update that list deliberately when roles change.

Not a merge-blocker for #205: production behaviour of the additive enum member is correct; this is test strength only.

Related

• PR: feat(core): add the non-custodial wallet partner user role #205
• Sequencing note from feat(core): add the non-custodial wallet partner user role #205: release should still follow DFXswiss/api#4587