fix: use Go 1.24 with GOTOOLCHAIN=auto for Docker build

Dockerfile

@@ -0,0 +1,42 @@
+# Build stage
+FROM golang:1.24-alpine AS builder
+
+ENV GOTOOLCHAIN=auto
+
+RUN apk add --no-cache git
+
+WORKDIR /app
+
+# Copy go mod files
+COPY server/go.mod server/go.sum ./
+RUN go mod download
+
+# Copy source code
+COPY server/ ./
+COPY agent/ ../agent/
+
+# Build server
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /nuyue-server ./cmd/server
+
+# Build agent
+RUN cd ../agent && CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /nuyue-agent ./cmd/agent
+
+# Runtime stage
+FROM alpine:3.19
+
+RUN apk add --no-cache ca-certificates tzdata
+
+WORKDIR /app
+
+# Copy binaries
+COPY --from=builder /nuyue-server /app/
+COPY --from=builder /nuyue-agent /app/
+
+# Copy frontend (built by CI)
+COPY server/embed/dist /app/embed/dist
+
+# Expose ports
+EXPOSE 8080 9090
+
+# Run server
+CMD ["/app/nuyue-server"]