[XinyuGuan]

Fixes #313.

math.min and math.max now fall back to the VM's __lt lookup when a pair cannot use primitive ordering. The numeric/string path, exact mixed integer/float comparisons from #142, first-argument checks, tie handling and original result identity are retained.

The fallback uses the existing async-native machinery. Arguments stay rooted in the native stack window; only slot indices cross calls, and only the comparator's first result is interpreted using Lua truthiness.

Adds eight regression cases checked against PUC Lua 5.5.1: tables and userdata, right-operand lookup/mixed types, truthiness, error-object propagation, GC and reentrant selection, live metatable changes, ties, and primitive/single-argument controls. Seven fail before the fix; all eight pass afterward.

Validation with the pinned Rust nightly 2026-04-05, Linux amd64:

• Full upstream CI command set passes: workspace tests, formatting, workspace/all-target Clippy, generic-table Clippy, and generic-table unit tests.
• All eight regressions pass in release mode and in a second clean checkout with the exact patch applied.
• The rebuilt CLI matches reference output for all eight programs, twice each. Additional comparisons cover a transition from primitive to metamethod ordering and a callable-table comparator.
• git diff --check passes.

This branch is based directly on upstream main and is independent of the unpack fix in #314.