refactor: Makefile 命名规范化，新增顶层便捷命令

统一命名规范为 <namespace>-<action>[-<variant>] 格式：
- 重命名 desktop-mac/win/linux → desktop-build-mac/win/linux
- 重命名 backend-migrate-* → backend-db-*
- 重命名 frontend-build-desktop → desktop-prepare-frontend
- 重命名 embedfs-prepare → desktop-prepare-embedfs
- 重命名 package-macos → desktop-package-mac

新增顶层便捷命令：
- dev: 并行启动开发环境
- build: 构建所有产物
- test: 运行所有测试
- lint: 检查所有代码
- clean: 清理所有构建产物

Makefile

@@ -1,22 +1,44 @@
-.PHONY: all clean \
-	backend-build backend-run backend-test backend-test-unit backend-test-integration backend-test-coverage \
-	backend-lint backend-deps backend-generate \
-	backend-migrate-up backend-migrate-down backend-migrate-status backend-migrate-create \
-	frontend-build frontend-dev frontend-test frontend-test-watch frontend-test-coverage frontend-test-e2e frontend-lint \
-	desktop-mac desktop-win desktop-linux package-macos
+.PHONY: all dev build test lint clean \
+	backend-build backend-run backend-dev backend-test backend-test-unit backend-test-integration backend-test-coverage \
+	backend-lint backend-clean backend-deps backend-generate \
+	backend-db-up backend-db-down backend-db-status backend-db-create \
+	frontend-build frontend-dev frontend-test frontend-test-watch frontend-test-coverage frontend-test-e2e frontend-lint frontend-clean \
+	desktop-build desktop-build-mac desktop-build-win desktop-build-linux \
+	desktop-dev desktop-package-mac desktop-package-win desktop-package-linux desktop-clean \
+	desktop-prepare-frontend desktop-prepare-embedfs
+
+# ============================================
+# 顶层便捷命令
+# ============================================
+
+dev:
+	@echo "🚀 Starting development environment..."
+	@$(MAKE) -j2 backend-dev frontend-dev
+
+build: backend-build frontend-build
+	@echo "✅ Build complete"
+
+test: backend-test frontend-test
+	@echo "✅ All tests passed"
+
+lint: backend-lint frontend-lint
+	@echo "✅ Lint complete"
+
+all: build test lint
 
 # ============================================
 # 后端
 # ============================================
 
-all: backend-build
-
 backend-build:
 	cd backend && go build -o bin/server ./cmd/server
 
 backend-run:
 	cd backend && go run ./cmd/server
 
+backend-dev:
+	cd backend && go run ./cmd/server
+
 backend-test:
 	cd backend && go test ./... -v
 
@@ -34,22 +56,25 @@ backend-test-coverage:
 backend-lint:
 	cd backend && go tool golangci-lint run ./...
 
+backend-clean:
+	rm -rf backend/bin/ backend/coverage.out backend/coverage.html
+
 backend-deps:
 	cd backend && go mod tidy
 
 backend-generate:
 	cd backend && go generate ./...
 
-backend-migrate-up:
+backend-db-up:
 	cd backend && goose -dir migrations sqlite3 $(DB_PATH) up
 
-backend-migrate-down:
+backend-db-down:
 	cd backend && goose -dir migrations sqlite3 $(DB_PATH) down
 
-backend-migrate-status:
+backend-db-status:
 	cd backend && goose -dir migrations sqlite3 $(DB_PATH) status
 
-backend-migrate-create:
+backend-db-create:
 	@read -p "Migration name: " name; \
 	cd backend && goose -dir migrations create $$name sql
 
@@ -78,35 +103,60 @@ frontend-test-e2e:
 frontend-lint:
 	cd frontend && bun run lint
 
+frontend-clean:
+	rm -rf frontend/dist frontend/.next frontend/node_modules
+
 # ============================================
 # 桌面应用
 # ============================================
 
-frontend-build-desktop:
-	cd frontend && cp .env.desktop .env.production.local && bun install && bun run build && rm -f .env.production.local
+desktop-build: desktop-build-mac desktop-build-win desktop-build-linux
+	@echo "✅ Desktop builds complete for all platforms"
 
-embedfs-prepare:
+desktop-prepare-frontend:
+	@echo "📦 Preparing frontend for desktop..."
+	cd frontend && cp .env.desktop .env.production.local
+	cd frontend && bun install && bun run build
+	rm -f frontend/.env.production.local
+
+desktop-prepare-embedfs:
+	@echo "📦 Preparing embedded filesystem..."
 	rm -rf embedfs/assets embedfs/frontend-dist
 	cp -r assets embedfs/assets
 	cp -r frontend/dist embedfs/frontend-dist
 
-desktop-mac: frontend-build-desktop embedfs-prepare
+desktop-build-mac: desktop-prepare-frontend desktop-prepare-embedfs
+	@echo "🍎 Building macOS..."
 	cd backend && CGO_ENABLED=1 GOOS=darwin GOARCH=arm64 go build -o ../build/nex-mac-arm64 ./cmd/desktop
 	cd backend && CGO_ENABLED=1 GOOS=darwin GOARCH=amd64 go build -o ../build/nex-mac-amd64 ./cmd/desktop
 
-desktop-win: frontend-build-desktop embedfs-prepare
+desktop-build-win: desktop-prepare-frontend desktop-prepare-embedfs
+	@echo "🪟 Building Windows..."
 	cd backend && CGO_ENABLED=1 GOOS=windows GOARCH=amd64 go build -ldflags "-H=windowsgui" -o ../build/nex-win-amd64.exe ./cmd/desktop
 
-desktop-linux: frontend-build-desktop embedfs-prepare
+desktop-build-linux: desktop-prepare-frontend desktop-prepare-embedfs
+	@echo "🐧 Building Linux..."
 	cd backend && CGO_ENABLED=1 GOOS=linux GOARCH=amd64 go build -o ../build/nex-linux-amd64 ./cmd/desktop
 
-package-macos:
+desktop-dev: desktop-prepare-frontend desktop-prepare-embedfs
+	@echo "🖥️  Starting desktop app in dev mode..."
+	cd backend && go run ./cmd/desktop
+
+desktop-package-mac:
 	./scripts/build/package-macos.sh
 
+desktop-package-win:
+	@echo "⚠️  Windows packaging not implemented yet"
+
+desktop-package-linux:
+	@echo "⚠️  Linux packaging not implemented yet"
+
+desktop-clean:
+	rm -rf build/ embedfs/assets embedfs/frontend-dist
+
 # ============================================
 # 清理
 # ============================================
 
-clean:
-	rm -rf backend/bin/ backend/coverage.out backend/coverage.html
-	rm -rf build/
+clean: backend-clean frontend-clean desktop-clean
+	@echo "✅ Clean complete"