Fix: Add binary compatibility forwarder for EventStream.recover

[nguyenyou]

Summary

• Add a single forwarding override for recover on EventStream
• Restores the Scala.js IR method descriptor that libraries compiled against Airstream 17.x expect

Fixes #149

Context

As diagnosed by @sjrd in this comment, RecoverOps[+Self[+_], +A] has Self without the <: Observable[_] upper bound that BaseObservable has. When recover moved to RecoverOps in 18.0.0-M3, the Scala.js IR method descriptor changed (erased return type went from Observable to Object), breaking binary compatibility for downstream libraries compiled against 17.x.

The fix is minimal: only EventStream.recover needs a forwarder, since caliban (the affected library) only calls .map and .recover on EventStream, and .map is already overridden.

Reproduction

https://github.com/nguyenyou/airstream-recover-bincompat-repro

Test plan

• All 309 Airstream tests pass
• Verified with minimal repro: library compiled against Airstream 17.2.1 now links successfully with the patched Airstream 18.x

🤖 Generated with Claude Code

[raquo]

Sorry, I don't think I'll be merging this after all. You've already worked around this locally, and nobody else has expressed interest in this. If I merge this, then yes, we'll get a bit of binary compatibility in v18 release, but then we'll have to break it again in the next release once we remove this forwarder (as I understand it). So it would just be delaying the breakage. Might as well be done with that now if it's not especially hurting anyone 🤷‍♂️