Add Makefile with build, test, run, and devrun targets

Makefile wraps Gradle commands and adds emulator/device launch targets:
- run: builds, starts DC-1 emulator if needed, installs and launches
- devrun: builds, installs and launches on connected USB device
- Updated CLAUDE.md and DESIGN.md source trees

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Makefile

@@ -0,0 +1,48 @@
+ANDROID_HOME ?= $(HOME)/Library/Android/sdk
+ADB          := $(ANDROID_HOME)/platform-tools/adb
+EMULATOR     := $(ANDROID_HOME)/emulator/emulator
+AVD          ?= DC-1
+PACKAGE      := net.metacircular.engpad
+ACTIVITY     := $(PACKAGE).MainActivity
+
+.PHONY: build test lint clean run devrun all
+
+# Build everything (compile + test + lint)
+all: lint test build
+
+# Compile debug and release APKs
+build:
+	./gradlew build
+
+# Run unit tests
+test:
+	./gradlew test
+
+# Run a single test class: make test-one CLASS=net.metacircular.engpad.data.StrokeBlobTest
+test-one:
+	./gradlew test --tests "$(CLASS)"
+
+# Run Android lint
+lint:
+	./gradlew lint
+
+# Clean build artifacts
+clean:
+	./gradlew clean
+
+# Install and launch on the Android emulator.
+# Starts the emulator if it isn't already running.
+run: build
+	@if ! $(ADB) devices | grep -q emulator; then \
+		echo "Starting emulator ($(AVD))..."; \
+		$(EMULATOR) -avd $(AVD) -no-snapshot-load &>/dev/null & \
+		$(ADB) wait-for-device; \
+		echo "Emulator ready."; \
+	fi
+	./gradlew installDebug
+	$(ADB) -e shell am start -n $(PACKAGE)/$(ACTIVITY)
+
+# Install and launch on a connected USB device.
+devrun: build
+	./gradlew installDebug
+	$(ADB) -d shell am start -n $(PACKAGE)/$(ACTIVITY)