feat: built-in tracing channel support

[pi0]

This PR adds a new nitro config tracing: true (or options) to enable built-in tracing channel support for internals.

Currently adding for h3 and srvx + db0 and unstorage comming soon thanks to @logaretm ❤️)

Node.js tracing channel is availabe in Node.js, Deno, Bun and also Cloudflare workers so it is kinda a universal and very lightweight standard for tracing events.

TODO:

• Node.js (prod)
• Deno and Bun
• Dev server (currently only h3 is traced, we need to migrate dev to srvx)
• Add tests

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Example events:

[tracing:h3.fetch] asyncStart event={app,req,url,context}, type=middleware, result=undefined
[tracing:h3.fetch] asyncEnd event={app,req,url,context}, type=middleware, result=undefined
[tracing:h3.fetch] asyncStart event={app,req,url,context}, type=middleware, result=undefined
[tracing:h3.fetch] asyncEnd event={app,req,url,context}, type=middleware, result=undefined
[tracing:srvx.fetch] asyncStart request={runtime,waitUntil,context}, server={runtime,options,node,serveOptions,fetch}, result=Response(200 OK)
[tracing:srvx.fetch] asyncEnd request={runtime,waitUntil,context}, server={runtime,options,node,serveOptions,fetch}, result=Response(200 OK)

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Project	Deployment	Actions	Updated (UTC)
nitro.build	Ready	Preview, Comment	Feb 5, 2026 11:37pm

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✨ Finishing touches

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• Create PR with unit tests
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• Commit unit tests in branch feat/tracing

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commit: b030a44