Code Simplification Refactoring (Feature 111)

Internal code quality maintenance release. This refactoring eliminates 16 code-quality findings — duplicate logic, dead code, unused parameters, and overly complex structures — without changing any user-visible output, CLI options, or API contracts.

♻️ Refactoring

This release is a pure internal refactoring. There are no new features, no bug fixes visible to users, and no changes to the tool's output or behaviour.

What changed internally:

• Shared AzDO mapper base class — AzdoGroupMapper, AzdoUserMapper, AzdoProjectMapper, and AzdoRepositoryMapper now inherit from a common AzdoEntityMapper abstract base, eliminating ~300 lines of duplicated structure.
• Shared AzDO formatter helper — AzdoGroupDescriptorFormatter, AzdoUserIdFormatter, AzdoProjectIdFormatter, and AzdoRepositoryIdFormatter now delegate to a single AzdoFormatterHelper.TryFormat method, reducing each class to a thin wrapper.
• ApplyViewModelContext record — The six-parameter ApplyViewModel interface method is replaced by a single context record, removing scattered _ = param discards across all factory implementations.
• Eliminated dead code — BuildDefinitionRenderer, VariableGroupFactory, BuildDefinitionFactory, ShouldUseMultilineDetailsSummary, and the unused principalMapper constructor parameter have been removed.
• Reduced duplicate dispatch — FormatAttributeValuePlain now delegates to TryFormatSemanticValue instead of duplicating its dispatch chain; IconProviderRegistry and ValueFormatterRegistry share a TryResolveFirst helper in PatternMatchingRegistry<T>.
• Modern C# idioms — ServiceResolutionContext and SummaryModel converted to sealed records; ActionSummary, SummaryModel, and ResourceTypeBreakdown tightened to internal access.
• Single BuildReferenceIndex call — Configuration reference index is built once per plan render and passed down, eliminating a redundant rebuild on each resource.

All 1186 tests pass. Snapshot output is unchanged.

🔗 Commits

• 6cf04ae refactor: introduce ApplyViewModelContext record (Tasks 1-2)
• 7848a1c refactor: AzDO mapper base class and formatter helper (Tasks 3-5)
• f3f7bf5 refactor: remove BuildDefinitionRenderer, vestigial factories, add TryGetFactory, remove unused registry params (Tasks 6-9)
• 925f789 Refactor Markdown Generation and Renderer Components
• 0bf53db refactor: fix pre-existing build errors from Tasks 1-16 and implement Tasks 17-22
• ef13637 refactor: convert ServiceResolutionContext to positional record
• 2856bd9 refactor: fix code review issues — remove unused principalMapper param, fix naming, add comment