feat(mcp): add breakability evaluation tool

[ShawkyZ]

Changes
Adds a new experimental tool to Snyk MCP Server for assessing SCA breakability changes for package upgrades

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

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✅	Code Security	0	0	0	0	0 issues

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[j-luong]

nitpick: can we add from the template: ## What's the product update that needs to be communicated to CLI users?

[snyk-pr-review-bot]

PR Reviewer Guide 🔍

🧪 No relevant tests

🔒 No security concerns identified

⚡ No major issues detected

📚 Repository Context Analyzed This review considered 3 relevant code sections from 3 files (average relevance: 0.80) scripts/upgrade-snyk-go-dependencies.go (lines 1-135) package-lock.json (lines 6-275) package.json (lines 1-224)