tests: add hello2, simple, banktest smoke tests

hello2 — stdio vs conio output API comparison (fast/no-attr vs
slower/attributed), also exercises textcolor/textbackground.
simple — packed 2-bit style array bit-twiddling smoke test.
banktest — __banked function calls across two explicit banks in huge
memory mode.

hello2.c updated to call the renamed gettextmode/settextmode (see the
conio rename in 5e5e70d).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/banktest/Makefile

@@ -0,0 +1,11 @@
+# Build banked.exe — HUGE memory mode (small + banked code in W3).
+#
+# Layout:
+#   CODE/HOME at 0x4100 (W1), DATA at 0x8000 (W2), banks at 0x{N}C000 (W3).
+#   crt0_banked.s loads N banks from the .EXE before calling main.
+
+PROJ_ROOT := $(abspath $(CURDIR)/../..)
+EXAMPLE   := banked
+MEMORY    := huge
+EXTRA_FLAGS := --bank 1=bank1.c --bank 2=bank2.c
+include $(PROJ_ROOT)/app.mk