fix: downgrade nanoid to v3 for CommonJS compatibility

nanoid v5 is ESM-only and cannot be require()'d in a CommonJS module.
v3 is the last version with native CJS support.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/backend/package.json

@@ -28,7 +28,7 @@
     "graphql-ws": "^6.0.4",
     "graphql-yoga": "^5.13.4",
     "ioredis": "^5.6.1",
-    "nanoid": "^5.1.5",
+    "nanoid": "^3.3.11",
     "nodemailer": "^7.0.3",
     "pg": "^8.16.0",
     "slugify": "^1.6.6",

pnpm-lock.yaml

@@ -56,8 +56,8 @@ importers:
         specifier: ^5.6.1
         version: 5.10.0
       nanoid:
-        specifier: ^5.1.5
+        specifier: ^3.3.11
-        version: 5.1.6
+        version: 3.3.11
       nodemailer:
         specifier: ^7.0.3
         version: 7.0.13
@@ -2283,11 +2283,6 @@ packages:
     engines: {node: ^10 || ^12 || ^13.7 || ^14 || >=15.0.1}
     hasBin: true
 
-  nanoid@5.1.6:
-    resolution: {integrity: sha512-c7+7RQ+dMB5dPwwCp4ee1/iV/q2P6aK1mTZcfr1BTuVlyW9hJYiMPybJCcnBlQtuSmTIWNeazm/zqNoZSSElBg==}
-    engines: {node: ^18 || >=20}
-    hasBin: true
-
   next-tick@1.1.0:
     resolution: {integrity: sha512-CXdUiJembsNjuToQvxayPZF9Vqht7hewsvy2sOWafLvi2awflj9mOC6bHIg50orX8IJvWKY9wYQ/zB2kogPslQ==}
 
@@ -4636,8 +4631,6 @@ snapshots:
 
   nanoid@3.3.11: {}
 
-  nanoid@5.1.6: {}
-
   next-tick@1.1.0: {}
 
   node-addon-api@8.6.0: {}