some backend fixes and add android app

Makefile

@@ -36,10 +36,22 @@ desktop-install: ## Install the launcher entry and icon for your user
 helper-install: ## Install the privileged blocking helper (asks for sudo)
 	sudo ./desktop/helper/install.sh
 
+android-test: ## Run every Android test (no device, no backend needed)
+	cd android && ./gradlew :core:test :app:testDebugUnitTest
+
+android-test-core: ## Run just the pure-logic suite (needs only a JDK)
+	cd android && ./gradlew :core:test
+
+android-build: ## Build the debug APK (needs the Android SDK)
+	cd android && ./gradlew :app:assembleDebug
+
+android-install: ## Install the debug APK on the connected phone
+	cd android && ./gradlew :app:installDebug
+
 report: ## Build and send today's report right now
 	cd backend && PYTHONPATH=$$PWD .venv/bin/python -m app.cli report
 
 set-password: ## Set/rotate the web login password (asks for a confirm)
 	docker compose exec app python -m app.cli set-password
 
-.PHONY: help up down logs dev test backend-venv web-build desktop desktop-install helper-install report set-password
+.PHONY: help up down logs dev test backend-venv web-build desktop desktop-install helper-install android-test android-test-core android-build android-install report set-password