SDK: Bump @sentinel-auth/nextjs peer dependency to include Next.js 16

[sidxz]

Problem

@sentinel-auth/nextjs@0.10.2 declares:

"peerDependencies": {
  "next": "^14.0.0 || ^15.0.0"
}

Next.js 16 is now stable (16.2.2). Installation produces:

WARN ✕ unmet peer next@"^14.0.0 || ^15.0.0": found 16.2.2

Fix

Update package.json in sdks/nextjs/:

- "next": "^14.0.0 || ^15.0.0"
+ "next": "^14.0.0 || ^15.0.0 || ^16.0.0"

Everything works correctly with Next.js 16 — this is purely a version constraint update.

Severity

Cosmetic — functional behavior is unaffected. But it causes noise in CI logs and strict package managers (pnpm strict-peer-dependencies=true) may refuse to install.

Discovered in

Chem-Vault2 frontend (S06) using @sentinel-auth/nextjs@0.10.2 + Next.js 16.2.2