Port SvelteKit E2E test apps to span streaming

[andreiborza]

Port these E2E test applications to span streaming (6 apps).

Apps

• sveltekit-2
• sveltekit-2-kit-tracing
• sveltekit-2-svelte-5
• sveltekit-2.5.0-twp
• sveltekit-3
• sveltekit-cloudflare-pages

What to do

For each app:

1. Remove the traceLifecycle: 'static' pin added in test(e2e): Disable span streaming in e2e test applications #22590 from every Sentry.init (client and server hooks).
2. Rewrite the specs from transaction envelopes to span v2:
   • waitForTransaction becomes waitForStreamedSpan / waitForStreamedSpans
   • event.transaction becomes span.name
   • contexts.trace.op becomes getSpanOp(span) plus span.is_segment
   • contexts.trace.data['x'] becomes span.attributes['x'], which has the shape { value, type }
   • transaction_info.source becomes the sentry.segment.name.source attribute
3. Streamed child spans arrive across several envelopes, so use collectStreamedSpans wherever a test asserts on children of a segment span.

SvelteKit router spans lose their SvelteKit Route Change name and become Router under streaming, so those assertions have to change. Also watch http.server names.

Reference apps: react-router-7-spa-streaming and nextjs-16-streaming. Worked example: #23797.

Keep static trace lifecycle coverage

Before porting this group, duplicate sveltekit-2 as-is into sveltekit-2-static and leave that copy on the current transaction-based specs. That keeps the static trace lifecycle covered once the rest of the group moves to streaming.

The copy is verbatim; only the app name changes:

• package.json -> name
• start-event-proxy.mjs -> proxyServerName
• every waitForTransaction / waitForError / waitForSession call in tests/

Keep traceLifecycle: 'static' in the copy's Sentry.init calls. The e2e matrix discovers apps by directory, so no CI config change is needed.

The representative is a suggestion: swap it if another app in the list exercises more of this SDK's instrumentation.

[linear-code]

JS-3492