Release v0.27.0

[shellrow]

What changed

• Make asynchronous networking APIs opt-in.
• Stabilize packet parsing, network interface, and socket configuration APIs.
• Add caller-controlled IPv4 identification and fallible packet builders with validation.
• Unify packet parsing errors and strictness handling.
• Improve packet parsing performance with allocation-free views and cached mutable layouts.
• Harden datalink, socket, raw descriptor, and FFI safety.
• Fix IPv6 extension padding and checksum handling across split buffers.
• Improve macOS BPF parsing and restore iOS and NetBSD socket compatibility.
• Load Npcap Packet.dll at runtime on Windows.
• Hide internal datalink backend modules and rename datalink fanout variants.
• Establish Rust 1.88 as the workspace MSRV.
• Expand parser robustness tests, benchmarks, and cross-platform CI coverage.
• Add workspace quality, feature-gate, and cargo-deny supply-chain checks.
• Update dependencies