v0.8.6

Performance

1. Deterministic release of LSS query result buffers. Series-id buffers allocated in C for querier results were previously kept alive by series sets and only freed by a Go GC finalizer. Because the real bytes live off the Go heap (jemalloc), finalization lagged and large over-allocated buffers piled up under query load. Series sets now carry the series id inline, so the query result can be closed as soon as construction finishes (#447).
2. Pooled buffers for WAL segment reads. Segment resize now reuses buffers from a size-class pool instead of allocating a fresh slice on every read, cutting allocation churn when loading WAL segments (#452).

Fixes

1. ActiveQueryTracker SIGBUS on sparse query-log files. Creating the active-queries mmap file via Truncate alone left a sparse file on some filesystems, so writes into the mapping could fault with SIGBUS. The file is now explicitly zero-filled (and synced) before mmap (#433).
2. DataStorage dummy-metrics static initialization race. When per-DataStorage metrics collection was disabled, concurrent construction could race on the shared inline-static dummy metrics page. The dummy is now a function-local static initialized on first use (#455).
3. Dependency security updates. Bumped Go modules github.com/klauspost/compress to v1.18.7 (#453) and go.opentelemetry.io/otel to v1.44.0 (#450), and the web UI postcss package to v8.5.18 (#449), picking up upstream security fixes.