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
sneak
75b57cfb29