feat: add node config generator

[tionis]

This addresses #51 and adds an init command as discussed in the issue

[Copilot]

Pull request overview

This PR implements the “node.yaml generator” from #51 by introducing a new nylon init CLI command that generates a node config (including a freshly generated private key) and prints the corresponding public key for use in central.yaml. It also tightens key deserialization by validating decoded key lengths and updates the Getting Started guide to use the new workflow.

Changes:

• Add nylon init command to generate node.yaml with secure file permissions and optional network/DNS/distribution/hook settings.
• Reject invalid private/public keys during YAML/text deserialization by enforcing expected decoded byte length.
• Update documentation and add tests covering init behavior and key-length validation.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
state/serialize.go	Adds decoded-length validation for private/public key text deserialization.
state/serialize_test.go	Adds regression tests ensuring wrong-length keys are rejected.
docs/guides/getting-started.mdx	Updates onboarding to use nylon init to generate node.yaml and keypair output guidance.
cmd/init.go	Implements the new init command and node-config construction/validation logic.
cmd/init_test.go	Adds tests for config generation, overwrite protection, dist option completeness, and validation errors.

Comments suppressed due to low confidence (2)

cmd/init.go:116

• For better UX and consistency with other commands (e.g., seal trims key files), trim whitespace from --key before base64-decoding. This makes nylon init --key "$(cat keyfile)" / copy-paste less error-prone.

	if opts.key != "" {
		if err := privateKey.UnmarshalText([]byte(opts.key)); err != nil {
			return nil, fmt.Errorf("invalid private key: %w", err)
		}
	}

cmd/init.go:148

• Trim whitespace from --dist-key before decoding so distribution bootstrap works reliably when users copy values from files/docs.

		var key state.NyPublicKey
		if err := key.UnmarshalText([]byte(opts.distKey)); err != nil {
			return nil, fmt.Errorf("invalid distribution key: %w", err)
		}

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[encodeous]

Perhaps we should use sudo here, so that the file is only readable by root

[tionis]

I was thinking of going more in the direction of using this to generate a config file and the user can just copy it to the right (root owned) location.

[encodeous]

I see, guess thats fair!

[encodeous]

I think what might be easier for the end user is to have an interactive CLI which asks the user for these flags. (We can still have the flags just for easy automation)

[tionis]

Sure, I can add such a flow.