release: prepare mlx-native 0.10.8

[robertelee78]

Summary

• bump mlx-native from 0.10.7 to 0.10.8
• make the merged family-neutral paired MoE large-prefill schedule primitive publishable for downstream hf2q
• keep the release additive and decode behavior unchanged

Exact local validation

• cargo check --locked --all-targets --all-features
• cargo +1.82.0 check --locked --lib
• cargo test --locked --test moe_pooled_pair_contract -- --test-threads=1 (1 passed)
• cargo +stable semver-checks check-release --baseline-version 0.10.7 (196 passed, no semver update required)
• cargo +1.96.0 package --locked twice from exact commit beac6e8c376c04ea261074b3fbf2647622f25e02
• candidate archive: 543 entries
• exact reproducible candidate SHA-256: 2179dd0d57c767c4407bc47de375fc0590ed10148b52a98ae2c08d8edbc728a8

The exact release workflow must regenerate the archive from the exact merged commit, test source and packed bytes, publish, and verify crates.io/GitHub bytes.