v0.0.4

Adds a concurrent, GC-evictable string interner alongside the single-writer arena pool, plus a cheap pool reset.

• Utf8StringInterner: a process-wide, thread-safe, self-bounding interner (hot/cold generation eviction) — the concurrent counterpart to Utf8StringPool. Managed-only; an outstanding Utf8String keeps its own bytes alive, so eviction never dangles a value already handed out.
• Utf8StringPool.Reset(): bulk reclaim and table clear for scoped reuse.
• OpenTelemetry metrics via Utf8StringInternerMetrics, an optional maximum value length that leaves oversized values uncached, and an untrusted-input hardening note.

See CHANGELOG.md for the full list.