nx_x86emit_gate.nx

nx_x86emit_gate.nx -- VERIFY the sovereign x86-64 emitter (nx_x86emit) by EMITTING functions through its api and EXECUTING them (cardinal rule 2: verify the primitive before the JIT rides it). Each test emits a tiny function via the SAME encoders the Sparkplug-tier JIT will use, casts the RWX buffer to a fn-ptr, calls it, and checks the result. Any encoding bug shows as a wrong value or a SIGSEGV/SIGILL here -- never silently in the JIT. Covers: reg-moves, imm32/imm64, arithmetic, imul, signed idiv (cqo+idiv), setcc booleanization, [base+disp] load/store, [base+index] SIB load/store (the VM stack access pattern), forward jcc + backward jmp (a real counted loop), and an indirect CALL through a register (the native->helper path). expect_exit: 0 license_tier: ORIGINAL