feat: add CAT/BAT (NUT-21/22) authentication support

[4xvgal]

Description

• This PR adds NUT-21/22 authentication support (CAT/BAT) to CoCo, enabling OIDC-based mint authentication via
  mgr.auth.*. It integrates cashu-ts AuthManager which handles the full CAT/BAT lifecycle (CAT
  storage/refresh, BAT auto-minting/pool management, DLEQ validation, per-endpoint NUT-21 vs NUT-22 detection).

  The CAT flow is fully functional end-to-end. BAT (Blind Auth Token) flow requires another repository to handle it

  Key changes:

  • Added AuthApi class that orchestrates per-mint cashu-ts AuthManager + OIDCAuth lifecycle
  • Added AuthSession model, AuthSessionRepository interface, and MemoryAuthSessionRepository
  • Added AuthSessionService for session CRUD with expiration validation and event emission
  • Extended MintAdapter with setAuthProvider/clearAuthProvider to inject AuthProvider into cashu-ts Mint constructor
    (auto-includes CAT/BAT headers in all HTTP requests)
  • Exposed as mgr.auth following existing Service -> API -> Manager pattern
  • Added domain errors: AuthSessionError, AuthSessionExpiredError
  • Added events: auth-session:updated, auth-session:deleted, auth-session:expired

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Notes to Reviewers

CAT Flow (working now): After mgr.auth.startDeviceAuth(mintUrl) or mgr.auth.login(mintUrl, tokens), the AuthProvider
is injected into MintAdapter. All subsequent Mint HTTP requests automatically include the Clear-auth header.
Session tokens are persisted via AuthSessionService and can be restored on app restart with
mgr.auth.restore(mintUrl).

BAT Flow (blocked): cashu-ts AuthManager handles BAT minting/pooling internally, but two things are
needed:

1. Multi-unit support merged (unit:'auth' keyset) — currently a separate PR
2. WalletService.buildWallet() needs to pass authProvider to its Mint instances

No Breaking Changes: All new APIs are additive. Existing code continues to work without modification.

No Database Migration Required: MemoryAuthSessionRepository is provided for tests. Platform storage adapters
(sqlite3, indexeddb, expo-sqlite) are tracked as future work.

API Changes

New: mgr.auth (AuthApi)

• mgr.auth.startDeviceAuth(mintUrl) — OIDC Device Code Flow; returns { verification_uri, user_code, poll(), cancel()
  }
• mgr.auth.login(mintUrl, tokens) — Manual login with externally obtained OIDC tokens
• mgr.auth.restore(mintUrl) — Restore persisted session on app restart; returns boolean
• mgr.auth.logout(mintUrl) — Delete session and disconnect AuthProvider
• mgr.auth.getSession(mintUrl) — Get valid (non-expired) session; throws if missing/expired
• mgr.auth.hasSession(mintUrl) — Check if session exists
• mgr.auth.getAuthProvider(mintUrl) — Get cashu-ts AuthProvider for advanced use

New: MintAdapter

• MintAdapter.setAuthProvider(mintUrl, provider) — Inject AuthProvider into Mint constructor
• MintAdapter.clearAuthProvider(mintUrl) — Remove AuthProvider and invalidate cached Mint

New: AuthSessionService

• AuthSessionService.saveSession(mintUrl, tokens) — Persist OIDC tokens as AuthSession
• AuthSessionService.getValidSession(mintUrl) — Get session with expiration check
• AuthSessionService.deleteSession(mintUrl) — Delete session
• AuthSessionService.hasSession(mintUrl) — Check existence

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Suggested CHANGELOG Updates

ADDED

• AuthSession model — { mintUrl, accessToken, refreshToken?, expiresAt, scope? }
• AuthSessionRepository interface — getSession, saveSession, deleteSession
• MemoryAuthSessionRepository — In-memory implementation for tests
• AuthApi class — NUT-21/22 authentication orchestrator (mgr.auth.*)
• AuthApi.startDeviceAuth(mintUrl) — OIDC Device Code Flow
• AuthApi.login(mintUrl, tokens) — Manual OIDC token login
• AuthApi.restore(mintUrl) — Session recovery on app restart
• AuthApi.logout(mintUrl) — Session cleanup
• AuthApi.getSession(mintUrl) / hasSession(mintUrl) — Session queries
• AuthApi.getAuthProvider(mintUrl) — Access cashu-ts AuthProvider
• AuthSessionService — Session CRUD + expiration validation + event emission
• AuthSessionError / AuthSessionExpiredError — Domain error classes
• auth-session:updated / auth-session:deleted / auth-session:expired — EventBus events
• MintAdapter.setAuthProvider() / clearAuthProvider() — AuthProvider injection
• 9 unit tests for AuthApi
• Integration test for OIDC Device Code Flow

MODIFIED

• Manager — Added readonly auth: AuthApi, wired in buildCoreServices / buildApis
• MintAdapter.getCashuMint() — Now passes authProvider to new Mint() constructor
• RepositoriesBase — Added authSessionRepository field
• AuthSessionService — Fixed Logger import (@nestjs/common → @core/logging)

Remaining Work (tracked in FEATURE_TODO.md)

• Storage adapters: sqlite3, indexeddb, expo-sqlite
• BAT persistence: AuthManager.exportPool() / importPool()
• WalletService authProvider wiring (depends on multi-unit merge)
• React wrapper hooks: useAuthSession(), useBatPool()

Test Coverage

Unit tests (9 new AuthApi tests, 441 total pass)
bun test packages/core/test/unit/AuthApi.test.ts

Integration test (requires mint with NUT-21/22 enabled + manual OIDC authorization)
MINT_URL=http://localhost:8085 bun test packages/core/test/integration/auth-session.test.ts --timeout 300000

I use customized oidc server nostr-oidc-ts for testing instead of KeyCloak
Which is pass cashu-ts AuthWallet device code flow test.

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