Port Svelte E2E test app to span streaming

[andreiborza]

Port this E2E test application to span streaming (1 app).

Apps

• svelte-5

What to do

1. Remove the traceLifecycle: 'static' pin added in test(e2e): Disable span streaming in e2e test applications #22590 from Sentry.init.
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.

This is plain Svelte with no router, so the pageload span falls back to the low-cardinality Pageload name instead of the URL path.

Reference app: react-router-7-spa-streaming. Worked example: #23797.

Keep static trace lifecycle coverage

Duplicate svelte-5 as-is into svelte-5-static and leave that copy on the current transaction-based specs. That keeps the static trace lifecycle covered once this app 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.

[linear-code]

JS-3499