VAPI-4167 fix: final in-call stats lost the call's inbound counters

[smoghe-bw]

Jira: VAPI-4167

Summary

• The gateway ends a call with a subscribe SDP re-offer that removes the call's track. onremovetrack fires during setRemoteDescription, so the "Final in-call stats (call ended)" read ran after the inbound-rtp stats were gone and always logged zero inbound counters, jitter: 0, codec: "unknown".
• handleSubscribeSdpOffer now reads a snapshot before setRemoteDescription while the in-call trace is running (inside the subscribe mutex), and keeps it only if complete.
• When the last call stream ends, that snapshot is logged as the final one. Without one, the fresh read is used as before.
• The stash is cleared on every trace stop and before each pre-offer read, so it never carries into a later call. Disconnect, signaling disconnected, connect and reconnect keep the fresh read, which still runs before the peer connections close.

Test plan

• npm test (175 passed)
• Re-offer that ends the call logs the pre-offer inbound values, and getStats runs before setRemoteDescription
• No read or stash on subscribe offers when no in-call trace runs
• A stash from one call is not used by a later call; disconnect still does a fresh final read
• Incomplete pre-offer read falls back to the fresh read

🤖 Generated with Claude Code

[bwappsec]

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