Add terminal simulator for previewing shows without hardware

Adds converter/simulate.py which renders the LED strip color live in the
terminal using ANSI 24-bit color, running the same step playback logic as
the Arduino firmware (blending, step timing, SHOW_LOOP/SHOW_SINGLE mode).
Keyboard controls mirror the physical button. Also adds 'make simulate'.

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

Makefile

@@ -19,7 +19,7 @@ PORT ?= $(shell arduino-cli board list 2>/dev/null | awk '/arduino:avr:uno/{prin
 
 # ---- Targets -----------------------------------------------------------
 
-.PHONY: all shows build upload port clean
+.PHONY: all shows simulate build upload port clean
 
 all: build
 
@@ -27,6 +27,10 @@ all: build
 shows:
 	python converter/convert_all.py
 
+## Preview shows in the terminal without hardware.
+simulate:
+	python converter/simulate.py
+
 ## Compile the sketch.
 build:
 	arduino-cli compile --fqbn $(FQBN) --build-path $(BUILD_DIR) $(SKETCH)