feat(server-utils): Add @opentelemetry/instrumentation-koa orchestrion integration

[s1gr1d]

Adds koaChannelIntegration in @sentry/server-utils for injecting orchestrion channels into koa.

A subscriber wraps each registered layer in a span-creating proxy.
Span-helpers are ported from the vendored instrumentation, preserving span names (but adapting to new conventions - check todo comments).

One thing to know for review: we instrument koa-compose, not use from koa. koa's use lives in koa's main entry (lib/application.js), and transforming a package's main entry forces its top-level require chain through Node's require(esm) bridge, which throws on Node < 24.13.

1. Orchestrion instruments by rewriting a module's source at load time (via the ESM load hook).
2. use lives in koa's main entry (lib/application.js), so to instrument it we transform that file. But transforming a main entry pulls its whole top-level require chain into the loader's handling --> and that changes how those requires are loaded (through the ESM→CommonJS translator, not the normal sync require path).
3. koa is CJS (but support ESM). When importing koa, it loads a shim that loads the CJS code: import 'koa' → dist/koa.mjs (a ESM shim) → import '../lib/application.js' (CJS). That CJS entry has a top-level require('is-generator-function').
4. is-generator-function → require('generator-function'), and generator-function points at an .mjs file, which in turn imports ./index.js.
   --> So the top-level require in koa's application.js (CJS) becomes require(esm) of an ESM file importing a CJS file.
5. On Node < 24.13 (we pin 20.19.5), the loader can't pre-link this dual-package shape into the require(esm) cache, so it throws request for './index.js' is not in cache.

The failing chain:

koa/lib/application.js (CJS)
  └─ require('is-generator-function')        (CJS)
       └─ require('generator-function')      → require(esm) → require.mjs (ESM)
            └─ import './index.js'            (ESM importing CJS)

koa-compose is koa's zero-dependency dispatch engine, so it's safe to transform, and compose(app.middleware) sees the same layers use would. Since @koa/router also calls compose per request, the subscriber uses getActiveSpan() to only wrap at app startup (no active span) and skip the per-request router composition.

Closes #20758

Linear: https://linear.app/getsentry/issue/JS-2409/rewrite-opentelemetryinstrumentation-koa-to-orchestrion

[github-actions]

size-limit report 📦

⚠️ Warning: Base artifact is not the latest one, because the latest workflow run is not done yet. This may lead to incorrect results. Try to re-run all tests to get up to date results.

Path	Size	% Change	Change
@sentry/browser	27.59 kB	-	-
@sentry/browser - with treeshaking flags	26.03 kB	-	-
@sentry/browser (incl. Tracing)	46.34 kB	-	-
@sentry/browser (incl. Tracing + Span Streaming)	48.13 kB	-	-
@sentry/browser (incl. Tracing, Profiling)	51.12 kB	-	-
@sentry/browser (incl. Tracing, Replay)	85.62 kB	-	-
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	75.26 kB	-	-
@sentry/browser (incl. Tracing, Replay with Canvas)	90.32 kB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback)	102.97 kB	-	-
@sentry/browser (incl. Feedback)	44.76 kB	-	-
@sentry/browser (incl. sendFeedback)	32.38 kB	-	-
@sentry/browser (incl. FeedbackAsync)	37.51 kB	-	-
@sentry/browser (incl. Metrics)	28.67 kB	-	-
@sentry/browser (incl. Logs)	28.91 kB	-	-
@sentry/browser (incl. Metrics & Logs)	29.59 kB	-	-
@sentry/react	29.38 kB	-	-
@sentry/react (incl. Tracing)	48.61 kB	-	-
@sentry/vue	33.03 kB	-	-
@sentry/vue (incl. Tracing)	48.3 kB	-	-
@sentry/svelte	27.61 kB	-	-
CDN Bundle	30 kB	-	-
CDN Bundle (incl. Tracing)	48.32 kB	-	-
CDN Bundle (incl. Logs, Metrics)	31.57 kB	-	-
CDN Bundle (incl. Tracing, Logs, Metrics)	49.64 kB	-	-
CDN Bundle (incl. Replay, Logs, Metrics)	70.81 kB	-	-
CDN Bundle (incl. Tracing, Replay)	85.84 kB	-	-
CDN Bundle (incl. Tracing, Replay, Logs, Metrics)	87.14 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback)	91.64 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)	92.92 kB	-	-
CDN Bundle - uncompressed	89.35 kB	-	-
CDN Bundle (incl. Tracing) - uncompressed	146.1 kB	-	-
CDN Bundle (incl. Logs, Metrics) - uncompressed	94.05 kB	-	-
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed	150.07 kB	-	-
CDN Bundle (incl. Replay, Logs, Metrics) - uncompressed	218.78 kB	-	-
CDN Bundle (incl. Tracing, Replay) - uncompressed	265.3 kB	-	-
CDN Bundle (incl. Tracing, Replay, Logs, Metrics) - uncompressed	269.26 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	279 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed	282.95 kB	-	-
@sentry/nextjs (client)	51.16 kB	-	-
@sentry/sveltekit (client)	46.78 kB	-	-
@sentry/core/server	78.42 kB	-	-
@sentry/core/browser	64.74 kB	-	-
@sentry/node-core	62.72 kB	-	-
@sentry/node	125.37 kB	-0.01%	-3 B 🔽
@sentry/node (incl. diagnostics channel injection)	139.06 kB	+0.38%	+516 B 🔺
@sentry/node/import (ESM hook with diagnostics-channel injection)	69.95 kB	-	-
@sentry/node/light	50.72 kB	-	-
@sentry/node - without tracing	74.06 kB	+0.01%	+1 B 🔺
@sentry/aws-serverless	85.5 kB	+0.01%	+1 B 🔺
@sentry/cloudflare (withSentry) - minified	181.71 kB	-	-
@sentry/cloudflare (withSentry)	449.16 kB	-	-

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