Language: Spaceship operator (<=>) for sorting and comparisons

[PurHur]

Problem

Sorting routes and records uses <=>. Not in compiler opcode set.

Goal

$a <=> $b returns -1, 0, or 1 for numbers and strings (PHP semantics).

Tasks

• Opcode + VM implementation
• JIT LLVM icmp/select chain
• PHPT with usort pattern (after Language: Implement foreach (CFG → VM → JIT) #53 foreach or VM sort builtin)
• Related to Compiler: VM/JIT comparison and equality for mixed types (routing guards) #90 mixed comparisons

Acceptance criteria

echo 1 <=> 2, 2 <=> 2, 3 <=> 2; → -101

Files

• lib/Compiler.php, lib/OpCode.php, lib/VM.php, lib/JIT.php