Add multi-tenant cloud mode: self-serve purchase, credit metering, core-decoupling

Introduces RECAP_MODE=multi alongside single-mode self-host:
- Tenant auth + accounts (magic-link via System SMTP), per-tenant credit pool,
  anonymous trial minting with per-IP/-64 caps
- Self-serve Pro/Max purchase: inline Lightning (BTCPay) + card (Zaprite),
  prepaid 30-day periods, expiry-reminder emails
- Core-decoupling: relay owns cloud tier/expiry keyed by Recaps user-id
- SQLite (better-sqlite3) schema for multi-mode; filesystem unchanged for single
- StartOS actions/versions through 0.2.155

startos/versions/v0.2.83.ts

@@ -0,0 +1,12 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_83 = VersionInfo.of({
+  version: '0.2.83:0',
+  releaseNotes: {
+    en_US: 'Optional password sign-in for multi-tenant tenants. Magic-link stays primary auth — visitors can keep using passwordless sign-in unchanged. Tenants who want a faster repeat sign-in can set a password in their lite settings (Account → Password) and then sign in with email + password from /auth.html. New endpoints: POST/DELETE /api/account/password (set / clear), POST /auth/signin-password (verify + issue session). scrypt hashes with per-password 16-byte salts; the timing-equalized verify path runs scrypt even on unknown emails so we don\'t leak existence. Minimum 8 chars, no composition rules. /api/account/whoami now reports has_password so the UI can branch on "Set" vs "Change / Remove" copy. Smoke-tested end-to-end before shipping.',
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})