feat(tools): add get_upgrade_guidance tool for UI5 Web Components migrations

[PetyaMarkovaBogdanova]

Add a new MCP tool that helps developers understand breaking changes and
migration requirements when upgrading UI5 Web Components between versions.

What's included:

• get_upgrade_guidance tool: Analyzes breaking changes between versions
  by fetching and parsing the official GitHub CHANGELOG. Returns structured
  migration guidance with affected components and recommendations.

• changelog_processor module: Core parsing logic including:

  • fetchChangelog(): Retrieves raw CHANGELOG from GitHub
  • resolveLatestVersion(): Queries npm registry for latest version
  • compareSemver(): Correctly compares semantic versions including pre-releases
  • parseChangelogRange(): Extracts version range (fromVersion, toVersion]
    with proper categorization of breaking changes, features, and bug fixes
  • formatUpgradeGuidance(): Generates markdown migration guide with summary,
    breaking changes, new features, and actionable migration checklist

• Type definitions: New interfaces for ChangelogEntry, VersionSection,
  and UpgradeGuidance to provide type-safe changelog data structures

• MCP Prompt registration: New 'upgrade-from-version' prompt that helps
  LLMs generate step-by-step migration checklists with code examples

• Comprehensive test suite: 27 unit tests covering:

  • Semantic version comparison (including pre-releases)
  • CHANGELOG range extraction with boundary conditions
  • Markdown formatting and output generation
  • Edge cases and error conditions

Features:

• Input validation to prevent invalid version strings
• Proper semantic versioning with pre-release support (rc, beta, etc.)
• Extracts per-component migration requirements
• Generates user-friendly migration checklists
• Robust error handling with clear user feedback
• Network error resilience with appropriate fallbacks

Technical notes:

• Range uses (fromVersion, toVersion] semantics: exclusive lower, inclusive upper
• Strips PR/commit links from descriptions for cleaner output
• Regex-based CHANGELOG parsing handles markdown formatting
• Fixture-based tests avoid network dependencies