fix(arm64): encode shifts, divides and multiplies and align sizes with emission

Assisted-by: GLM 5.3

testdata/verify/movimm2_arm64.s

@@ -0,0 +1,28 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Wide MOV immediates that expand past one instruction, each followed by a
+// branch to a later label: the displacement is what the two passes must agree
+// on, so a size pass that disagrees with the encoder corrupts the branch.
+// Byte-parity-checked against go tool asm.
+
+#include "textflag.h"
+
+TEXT ·movimm2(SB), NOSPLIT, $0-24
+	MOVW $-1, R0
+	B    after1
+	MOVD $0x0001000200030004, R1
+	B    after2
+	MOVD $0x0001000200030000, R2
+	B    after3
+	MOVW $0xFFFFFFFF, R3
+
+after1:
+	MOVD R0, r0+0(FP)
+
+after2:
+	MOVD R1, r1+8(FP)
+
+after3:
+	MOVD R2, r2+16(FP)
+	RET