Adds the `inline_asm: InlineAsm` opcode to the IR Op union (inst.zig): interned
template + operand list (role/name/constraint/operand) + interned clobber names
+ has_side_effects; the result rides on Inst.ty (void / scalar / tuple).
The new variant forces coverage in the exhaustive Op switches:
- interp.zig: loud bailDetail — inline asm is never comptime-evaluable.
- print.zig: an IR-dump arm.
- emit_llvm.zig: a @panic TRIPWIRE — emit lands in Phase D, and until then
lowerAsmExpr still bails, so no inline_asm op is ever created. Reaching emit
would mean lowering switched over before emit was ready; crash loudly rather
than miscompile.
No behavior change: lowering still bails, the op is constructed only in the new
`inline_asm op shape` unit test (inst.test.zig).
zig build test green (652 corpus, 446 unit).
6c08de8ec1