feat: renovate support for kubara catalogs

[tuunit]

📝 Summary

• Adds a renovate config example to the docs
• Adds a automatically generated added renovate config when running kubara init

🧩 Type of change

• 🔧 CLI / Go code
• 📝 Documentation
• 🧪 Test or CI change
• ♻️ Refactor / cleanup

⚠️ Is this a breaking change?

• Yes, this change breaks existing functionality (explain in summary)

🧪 Testing

• CI passed
• Manually tested (local/dev cluster)
• Unit tested
• Not tested (explain why below)

🔗 Additional Context / Related Issues / Tickets

✅ Checklist

• Code compiles and passes all tests
• Linting and style checks pass
• Comments added for complex logic
• Documentation updated (if applicable)

[Copilot]

Pull request overview

This PR adds first-class Renovate support for keeping OCI catalog references up to date, by (1) documenting a Renovate custom manager configuration and (2) auto-generating a renovate.json alongside the config when running kubara init.

Changes:

• Generate a renovate.json during kubara init (new ensureRenovateConfig helper).
• Document a Renovate custom manager + package rules configuration for catalog OCI references.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/cmd/init.go	Adds automatic renovate.json generation during init and the underlying generator logic.
docs/content/2_concepts/catalog_distribution.md	Adds an example Renovate config for automatic catalog updates.

Comments suppressed due to low confidence (1)

src/cmd/init.go:276

• ensureRenovateConfig is executed before the "config already exists" short-circuit and before env validation. As a result, kubara init can write renovate.json even when it subsequently returns an error (e.g., invalid env). Consider generating it only in the success paths (existing config, or after building the new cluster) instead of unconditionally at the top.

	if err := o.ensureRenovateConfig(cs); err != nil {
		return err
	}

	if fileExists {

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

docs/content/2_concepts/catalog_distribution.md:203

• The Renovate JSON example escapes the backtick as \\`` inside the regex character class, which makes the shown regex differ from the one generated by kubara init` and adds an unnecessary escape sequence for Renovate's JS regex engine. Keeping the example aligned with the generated config avoids copy/paste confusion.

      "matchStrings": ["oci:\\/\\/(?<depName>[^:\\s\"'\\`]+):(?<currentValue>[^\\s\"'\\`]+)"],

src/cmd/init.go:274

• ensureRenovateConfig runs before the envValidateErr early-return in normal mode, so kubara init can generate renovate.json even when init ultimately fails due to invalid env and no config is written. This leaves partial side effects on error paths.

	if err := o.ensureRenovateConfig(cs); err != nil {
		return err
	}