Drops the 0.15 REST management API and routes all account/auth/crypto/
principal operations through Stalwart 0.16's schema-driven JMAP
endpoint via a single passthrough (/api/account/stalwart/jmap).
- New client helper `stalwartJmap` + typed `requireResult`
- account-security-store rewritten against x:AccountPassword, x:AppPassword,
x:AccountSettings, x:Account (with currentSecret for TOTP ops)
- Client-side TOTP setup via `otpauth`; server-generated app password
secrets shown once on create
- Admin check switched to /api/account permissions
(sysAccountQuery/sysTenantQuery/sysSystemSettingsGet)
- Removed sieve vacation-overwrite workaround (fixed upstream #1251)
- Deleted old REST routes, StalwartClient, stale tests; added new
tests for passthrough + store
