refactor(repo): consolidate openflare-server to root and move subprojects to internal/apps

- Merge all files inside openflare-server to the repository root directory.
- Relocate agent, relay, and flared subprojects from internal/ to internal/apps/.
- Combine docker-compose files and update build context paths to root.
- Update GitHub workflows and Dockerfiles to refer to new directories and package names.
- Rewrite Go package imports across all files.
- Resolve database renew test race condition and clean up docs.

Makefile

@@ -0,0 +1,80 @@
+.PHONY: swagger license license-check build-embedded build-test cross-build code-check
+
+VERSION ?= dev
+BUILD_DATE ?= $(shell date -u +'%Y-%m-%dT%H:%M:%SZ')
+MODULE := $(shell go list -m)
+
+swagger:
+	scripts/swagger.sh
+
+license:
+	scripts/update_go_license.sh
+
+license-check:
+	scripts/update_go_license.sh --check
+
+build-embedded:
+	@echo "==> Building embedded frontend version=$(VERSION) build_date=$(BUILD_DATE)..."
+	cd frontend && \
+		NEXT_PUBLIC_APP_VERSION="$(VERSION)" \
+		NEXT_PUBLIC_APP_BUILD_DATE="$(BUILD_DATE)" \
+		pnpm build:embed
+	rm -rf internal/router/root/dist
+	cp -R frontend/out internal/router/root/dist
+	go build \
+		-tags embed_frontend \
+		-ldflags "-s -w -X '$(MODULE)/internal/buildinfo.Version=$(VERSION)' -X '$(MODULE)/internal/buildinfo.BuildTime=$(BUILD_DATE)'" \
+		-o bin/wavelet \
+		main.go
+
+code-check:
+	golangci-lint run
+	cd frontend && pnpm tsc --noEmit --jsx preserve && npx eslint . --max-warnings 0
+
+build-backend:
+	@echo "==> Building backend version=$(VERSION) build_date=$(BUILD_DATE)..."
+	go build \
+		-ldflags "-s -w -X '$(MODULE)/internal/buildinfo.Version=$(VERSION)' -X '$(MODULE)/internal/buildinfo.BuildTime=$(BUILD_DATE)'" \
+		-o bin/wavelet \
+		main.go
+
+build-frontend:
+	@echo "==> Building frontend version=$(VERSION) build_date=$(BUILD_DATE)..."
+	cd frontend && \
+		NEXT_PUBLIC_APP_VERSION="$(VERSION)" \
+		NEXT_PUBLIC_APP_BUILD_DATE="$(BUILD_DATE)" \
+		pnpm build:embed
+
+build-test:
+	@echo "==> Running frontend and backend build tests in parallel..."
+	@PIDS=""; \
+	STATUS=0; \
+	( cd frontend && pnpm build:embed 2>&1 | sed 's/^/[frontend] /' ) & PIDS="$$PIDS $$!"; \
+	( go test ./... && go build -o /dev/null ./... 2>&1 | sed 's/^/[backend]  /' ) & PIDS="$$PIDS $$!"; \
+	for PID in $$PIDS; do \
+		wait $$PID || STATUS=1; \
+	done; \
+	if [ $$STATUS -eq 0 ]; then \
+		echo "==> All build tests passed."; \
+	else \
+		echo "==> Build test FAILED." >&2; \
+		exit 1; \
+	fi
+
+cross-build:
+	@echo "==> Cross-compiling \
+	$(if $(GOOS),$(GOOS),linux/darwin/windows) × \
+	$(if $(GOARCH),$(GOARCH),amd64/arm64) \
+	(version=$(or $(VERSION),dev))..."
+	@mkdir -p bin
+	docker build \
+		--file docker/Dockerfile.cross \
+		--target export \
+		--build-arg VERSION=$(or $(VERSION),dev) \
+		--build-arg BUILD_DATE="$(shell date -u +'%Y-%m-%dT%H:%M:%SZ')" \
+		$(if $(GOOS),--build-arg TARGET_OS=$(GOOS)) \
+		$(if $(GOARCH),--build-arg TARGET_ARCH=$(GOARCH)) \
+		--output type=local,dest=./bin \
+		.
+	@echo "==> Done. Binaries written to ./bin/"
+	@ls -lh bin/