v0.3.2

fix(server): drop stale audio frame deferred across a stream clear/end

A frame deferred under send backpressure (5ms retry) could fire after a
stream/clear (seek) or stream/end, jumping the queue and injecting a stale
pre-seek frame into the post-clear stream. Bump a per-session streamGeneration
on clear/end and skip the deferred send if it changed — mirrors the reference
server's epoch invalidation. Bump version to 0.3.2.