feat(auth): admin TOTP MFA — enrollment, login challenge, recovery, CLI reset

Backend for #738. Real TOTP 2FA for admin accounts, all roles incl.
super_admin (closes #735).

- mfaService: otplib TOTP; AES-256-GCM encryption of the secret at rest
  (key derived from MFA_ENCRYPTION_KEY or JWT_SECRET); bcrypt-hashed,
  single-use recovery codes; otpauth URI + QR.
- Migration 151: adds two_factor_recovery_codes + two_factor_enrolled_at
  (secret/enabled columns already existed from legacy 016).
- Enrollment endpoints (behind adminAuth, per-user): GET /mfa/status,
  POST /mfa/{setup,enable,disable,recovery-codes}. Disable/regenerate
  require a current code so a hijacked session can't strip 2FA.
- Login challenge: /admin/login returns {mfaRequired, mfaToken} (no
  session) when 2FA is on; /admin/login/mfa exchanges a TOTP or recovery
  code for the session. Lockout counter is NOT reset until the second
  factor passes, so MFA brute-force is rate-limited too.
- CLI break-glass: scripts/reset-admin-mfa.js --email <e> | --all --yes,
  audit-logged, matches reset-admin-password.js convention.
- Docs + optional MFA_ENCRYPTION_KEY env.

Verified end-to-end on a live backend: enroll (super_admin), challenge,
TOTP + single-use recovery login, disable, and CLI reset.

backend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "picpeak-backend",
-  "version": "3.74.0-beta.0",
+  "version": "3.80.0-beta.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "picpeak-backend",
-      "version": "3.74.0-beta.0",
+      "version": "3.80.0-beta.0",
       "dependencies": {
         "@aws-sdk/client-s3": "^3.850.0",
         "@aws-sdk/lib-storage": "^3.850.0",
@@ -40,6 +40,7 @@
         "node-cron": "^3.0.2",
         "node-stream-zip": "^1.15.0",
         "nodemailer": "^9.0.1",
+        "otplib": "^12.0.1",
         "pdf-lib": "^1.17.1",
         "pdfkit": "^0.17.2",
         "pg": "^8.16.3",
@@ -2703,6 +2704,56 @@
         "node": ">=10"
       }
     },
+    "node_modules/@otplib/core": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/@otplib/core/-/core-12.0.1.tgz",
+      "integrity": "sha512-4sGntwbA/AC+SbPhbsziRiD+jNDdIzsZ3JUyfZwjtKyc/wufl1pnSIaG4Uqx8ymPagujub0o92kgBnB89cuAMA==",
+      "license": "MIT"
+    },
+    "node_modules/@otplib/plugin-crypto": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/@otplib/plugin-crypto/-/plugin-crypto-12.0.1.tgz",
+      "integrity": "sha512-qPuhN3QrT7ZZLcLCyKOSNhuijUi9G5guMRVrxq63r9YNOxxQjPm59gVxLM+7xGnHnM6cimY57tuKsjK7y9LM1g==",
+      "deprecated": "Please upgrade to v13 of otplib. Refer to otplib docs for migration paths",
+      "license": "MIT",
+      "dependencies": {
+        "@otplib/core": "^12.0.1"
+      }
+    },
+    "node_modules/@otplib/plugin-thirty-two": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/@otplib/plugin-thirty-two/-/plugin-thirty-two-12.0.1.tgz",
+      "integrity": "sha512-MtT+uqRso909UkbrrYpJ6XFjj9D+x2Py7KjTO9JDPhL0bJUYVu5kFP4TFZW4NFAywrAtFRxOVY261u0qwb93gA==",
+      "deprecated": "Please upgrade to v13 of otplib. Refer to otplib docs for migration paths",
+      "license": "MIT",
+      "dependencies": {
+        "@otplib/core": "^12.0.1",
+        "thirty-two": "^1.0.2"
+      }
+    },
+    "node_modules/@otplib/preset-default": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/@otplib/preset-default/-/preset-default-12.0.1.tgz",
+      "integrity": "sha512-xf1v9oOJRyXfluBhMdpOkr+bsE+Irt+0D5uHtvg6x1eosfmHCsCC6ej/m7FXiWqdo0+ZUI6xSKDhJwc8yfiOPQ==",
+      "deprecated": "Please upgrade to v13 of otplib. Refer to otplib docs for migration paths",
+      "license": "MIT",
+      "dependencies": {
+        "@otplib/core": "^12.0.1",
+        "@otplib/plugin-crypto": "^12.0.1",
+        "@otplib/plugin-thirty-two": "^12.0.1"
+      }
+    },
+    "node_modules/@otplib/preset-v11": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/@otplib/preset-v11/-/preset-v11-12.0.1.tgz",
+      "integrity": "sha512-9hSetMI7ECqbFiKICrNa4w70deTUfArtwXykPUvSHWOdzOlfa9ajglu7mNCntlvxycTiOAXkQGwjQCzzDEMRMg==",
+      "license": "MIT",
+      "dependencies": {
+        "@otplib/core": "^12.0.1",
+        "@otplib/plugin-crypto": "^12.0.1",
+        "@otplib/plugin-thirty-two": "^12.0.1"
+      }
+    },
     "node_modules/@paralleldrive/cuid2": {
       "version": "2.3.1",
       "resolved": "https://registry.npmjs.org/@paralleldrive/cuid2/-/cuid2-2.3.1.tgz",
@@ -9371,6 +9422,17 @@
         "node": ">= 0.8.0"
       }
     },
+    "node_modules/otplib": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/otplib/-/otplib-12.0.1.tgz",
+      "integrity": "sha512-xDGvUOQjop7RDgxTQ+o4pOol0/3xSZzawTiPKRrHnQWAy0WjhNs/5HdIDJCrqC4MBynmjXgULc6YfioaxZeFgg==",
+      "license": "MIT",
+      "dependencies": {
+        "@otplib/core": "^12.0.1",
+        "@otplib/preset-default": "^12.0.1",
+        "@otplib/preset-v11": "^12.0.1"
+      }
+    },
     "node_modules/p-limit": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-3.1.0.tgz",
@@ -11668,6 +11730,14 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/thirty-two": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/thirty-two/-/thirty-two-1.0.2.tgz",
+      "integrity": "sha512-OEI0IWCe+Dw46019YLl6V10Us5bi574EvlJEOcAkB29IzQ/mYD1A6RyNHLjZPiHCmuodxvgF6U+vZO1L15lxVA==",
+      "engines": {
+        "node": ">=0.2.6"
+      }
+    },
     "node_modules/thread-stream": {
       "version": "4.2.0",
       "resolved": "https://registry.npmjs.org/thread-stream/-/thread-stream-4.2.0.tgz",