Next.js 16.2.0-canary.63: React Debug Channel and Error Handling v16.2.0-canary.63

React Debug Channel is now on by default, unstable_retry() landed in error.js for better resilience, and we've tightened up prefetching for Cache Components on initial loads. Turbopack got some love too: faster builds without collect-build-traces overhead, cleaner codeframes in devtools, and less dynamic manifest paths. Ship it.