fix: stop BPF ring-buffer polling goroutine on trace end to prevent leak

setupEventChannel now returns the *bpf.RingBuffer handle alongside the
event channel. Both callers (runTraceWithContext, runHeadlessParquet)
defer rb.Stop() so the libbpfgo polling goroutine and C ring_buffer
struct are released promptly when the trace context is cancelled,
rather than waiting for bpfModule.Close() to eventually call rb.Close().
rb.Stop() and rb.Close() are both idempotent, so the double-call from
the defer and from bpfModule.Close() is safe.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions