shell-chain v0.24.3

[0.24.3] — 2026-06-13 — CI parity hardening

Fixed

• Event-loop unit tests under socket-restricted sandboxes: Node::run now
  supports disabling JSON-RPC startup through NodeConfig::rpc_enabled while
  preserving RPC startup by default for normal node operation. Event-loop tests
  that do not exercise RPC disable it explicitly, removing sandbox-only
  Operation not permitted bind failures from make ci.

Included after PR #70

• Hardened post-audit network bandwidth tests against token-bucket refill timing jitter.
• Added focused network invariant gates to make ci.