Populate trace_ids in replay events to enable searching replays by trace ID

[sentry-junior]

Problem

When searching for replays by trace ID in Sentry's Explore UI, replays from Dart/Flutter apps are not discoverable. The SDK doesn't collect or include trace_ids in replay events.

Solution

When a transaction is captured while replay is recording, the trace ID should be registered with the replay system and included in the next replay segment's trace_ids field.

Reference implementations

• JS: https://github.com/getsentry/sentry-javascript/blob/30eb68fff5077211c30c61ba74625e66ab514870/packages/replay-internal/src/coreHandlers/handleAfterSendEvent.ts#L34-L43
• Java: fix(replay): Associate trace IDs with replay segments sentry-java#5473

Key points

• Collect trace IDs when transactions are successfully captured during replay recording
• Limit to max 100 trace IDs per segment (matching JS SDK)
• Clear collected trace IDs after each segment is sent

Note

Since Flutter delegates replay to native SDKs, this may need coordination with sentry-java (Android) and sentry-cocoa (iOS) implementations, plus a mechanism to pass trace IDs from Dart transactions to the native replay system.

Action taken on behalf of Roman Zavarnitsyn.

[linear-code]

DART-379

[github-actions]

A PR closing this issue has just been released 🚀

This issue was referenced by PR #3744, which was included in the 9.22.0 release.

[buenaflor]

Re-opened for cocoa implementation later