perf(dev): Lazy load heavy modules in next-dev.ts
Defer loading of heavy modules until they're actually needed:
- Telemetry: loaded only in handleSessionStop
- loadConfig: loaded only when config is needed
- findPagesDir: loaded only in handleSessionStop
- getNpxCommand: loaded only for @next/font warning
- createSelfSignedCertificate: loaded only with --experimental-https
- uploadTrace: loaded only with --experimental-upload-trace
This reduces CLI startup time by avoiding synchronous import of
modules that may not be used in all code paths.
Also adds support for NEXT_CPU_PROF_DIR env var for profiling and
switches to using bundled dev server with optional bytecode caching.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
