chore(yarn): bump to 4.16.0 + vendor the release binary

Bumps yarn 4.12.0 -> 4.16.0 (fleet lockstep) and commits the vendored
.yarn/releases binary, which yarnPath references but was never tracked
(was relying on corepack — the house rule is vendored, no corepack).

Author: eetu

frontend/.yarn/releases/yarn-4.16.0.cjs

@@ -1,5 +1,14 @@
+approvedGitRepositories:
+  - "**"
+
 compressionLevel: mixed
 
 enableGlobalCache: false
 
+enableScripts: true
+
 nodeLinker: node-modules
+
+npmMinimalAgeGate: 0
+
+yarnPath: .yarn/releases/yarn-4.16.0.cjs

frontend/.yarnrc.yml

@@ -48,5 +48,5 @@
     "vitest": "^4.1.7",
     "vitest-browser-react": "^2.2.0"
   },
-  "packageManager": "yarn@4.12.0"
+  "packageManager": "yarn@4.16.0"
 }

frontend/package.json

@@ -2,7 +2,7 @@
 # Manual changes might be lost - proceed with caution!
 
 __metadata:
-  version: 8
+  version: 10
   cacheKey: 10
 
 "@babel/code-frame@npm:^7.0.0, @babel/code-frame@npm:^7.28.6, @babel/code-frame@npm:^7.29.0":