fix: correct golangci-lint v2 module path in Dockerfile

golangci-lint v2 uses module path github.com/golangci/golangci-lint/v2/...
Also set CGO_ENABLED=0 for Alpine compatibility.

Closes #13

Dockerfile

@@ -10,7 +10,7 @@ RUN go mod download
 COPY . .
 
 # Run all checks — build fails if branch is not green
-RUN go install github.com/golangci/golangci-lint/cmd/golangci-lint@v2.1.6
+RUN CGO_ENABLED=0 go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.1.6
 RUN make check
 
 ARG VERSION=dev