feat(arnitech): handlers for a 65816's native-mode interrupts on a Blade

A Blade reads the 65816's native-mode vectors from the RAM under the KERNAL
at $FFE4-$FFEF. native_vectors_init puts handlers' addresses there: IRQ and
NMI save A, X, and Y at full width, the direct page, and the data bank, push
the frame an emulation-mode interrupt makes, and run the KERNAL's handlers
through CINV and NMINV in 8-bit native mode, whose RTI comes back to restore
everything. BRK, COP, and ABORT go to the BRK handler, which on a Blade first
sets the direct page and data bank to 0 and returns to emulation mode.

src/aliases/,aliases_hardware_arnitech.s

@@ -33,3 +33,10 @@
 	!addr RRNET_TX_CMD         = $DE0C  ; write-only
 	!addr RRNET_TX_LENGTH      = $DE0E  ; write-only
 }
+
+!ifdef CONFIG_ARNITECH_BLADE {
+
+	; The 65816's native-mode vectors, which a Blade reads from the RAM under the KERNAL (ADR 0029)
+
+	!addr NATIVE_VECTORS       = $FFE4  ; COP, BRK, ABORT, NMI, reserved, IRQ
+}