Fix MeshCoreSession response and error miscorrelation

[robekl]

Summary

This PR fixes MeshCoreSession request/response miscorrelation by tightening how active commands accept success and error events.

The implementation is organized as a small series:

1. Serialize generic MeshCore command responses
2. Tighten typed MeshCore response matching
3. Correlate routed MeshCore binary responses by node
4. Correlate contact and private-key responses
5. Simplify request serializer release
6. Align MeshCoreSession docs with response matching
7. Fail fast on binary MeshCore request errors

What changed

• serialize generic command/ack waits so overlapping requests cannot steal each others .ok / .error events
• stop treating unrelated .error events as belonging to the active request in generic and typed request paths
• require exact typed-response matches where the protocol provides enough identity
• correlate routed status/telemetry binary responses by node prefix
• require getContact(publicKey:) to match the requested public key
• require importPrivateKey(_) to accept only bare .ok(nil) as success
• keep serialized binary requests fail-fast on device .error so an early rejection cannot stall the binary request serializer
• simplify serializer cleanup with defer { release() }
• align affected comments/docs with the current response-matching behavior

Notes on scope

A few APIs are still only serialized rather than fully correlated because the wire protocol does not expose enough identity to distinguish an unsolicited same-type event from the intended response. This PR only fixes the cases that can be made correct without inventing protocol semantics.

Binary requests intentionally remain a separate class from generic typed waits: they still fail immediately on device .error, because ignoring that event can strand the serialized binary request pipeline.

Tests

Added or updated regression coverage in MeshCoreSessionCommandCorrelationTests for:

• concurrent generic command serialization
• ignoring .ok responses with payloads for simple commands
• ignoring unrelated .error during start() and getBattery()
• ignoring wrong-node telemetry/status responses
• ignoring wrong-index channelInfo
• ignoring wrong-key contact
• ignoring .ok(value:) during importPrivateKey
• failing fast on binary request .error before messageSent
• releasing the binary request serializer after a binary request error

Validation run on the branch:

• cd MeshCore && swift test
• cd MC1Services && swift test
• xcodebuild -project MC1.xcodeproj -scheme MC1 -destination "platform=iOS Simulator,name=iPhone 16e" test

Latest binary-request follow-up additionally revalidated with:

• cd MeshCore && swift test --filter MeshCoreSessionCommandCorrelationTests
• cd MC1Services && swift test

[Avi0n]

Nice, thank you. Since this one has quite a few commits, could you squash them for me? Just to make the git history look a little cleaner.

[robekl]

Superseded by #264, which contains the same MeshCoreSession correlation fix as a single squashed commit plus the event-wait subscription hang fix found during validation.