Adds fast-srp-hap (the same SRP library Ente's web client uses, pinned
to 2.0.4) as a runtime dependency.
Tests build a full mock Ente server using fast-srp-hap's SrpServer to
exercise real SRP-6a math end-to-end. The mock handles:
GET /users/srp/attributes
POST /users/srp/create-session
POST /users/srp/verify-session
POST /users/two-factor/verify
POST /users/ott
POST /users/verify-email
7 tests covering:
* SRP login completing successfully
* SRP login requiring TOTP (returns { kind: 'totp' })
* Wrong password (SRP M1 fails server-side checkM1)
* Email MFA fallback (returns { kind: 'emailOTP' })
* submitTOTP
* requestEmailOTP + submitEmailOTP
Tests for the password-only decryption chain that follows a successful
login (SRP or email OTP, with or without 2FA). The unwrap covers:
password -> KEK (Argon2id) -> masterKey (secretbox) ->
secretKey (secretbox) -> tokenBytes (sealed box) -> base64url token
Each test builds a synthetic AuthorizationResponse using libsodium
directly and asserts unwrapAuth recovers the inputs byte for byte. The
test file also functions as the canonical description of the protocol.
Adds src/auth/types.ts with KeyAttributes, SRPAttributes,
AuthorizationResponse, and LoginChallenge declarations matching the
README's API reference. src/auth/unwrap.ts is the throwing stub; the
real implementation lands next.
