feat: add cobra CLI with input/output flags and debug option

- Add --input/-i and --output/-o flags for file selection
- Add --debug flag to print intermediate JSON to stderr
- Print errors during parsing

go.sum

@@ -0,0 +1,10 @@
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+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=