Add mock generation for @Instantiable types

[dfed]

Summary

SafeDI now automatically generates mock() methods for @Instantiable types, with full dependency tree support including Instantiator<T>, erasedToConcreteExistential, and @Forwarded properties.

New features

• Mock generation: Each @Instantiable type gets a mock() static method that builds its full dependency subtree inline, with every node overridable via optional closure parameters
• SafeDIMockPath enums: CapitalCase nested enums per dependency type describe where each dependency is created in the tree (case parent, case root, case childA, etc.)
• Instantiator<T> support: Mock wraps inline tree in Instantiator { forwarded in ... } closure. Forwarded properties become closure parameters. Transitive deps flow through from parent scope.
• erasedToConcreteExistential support: Auto-wraps concrete types in erased wrappers (e.g., AnyUserService(DefaultUserService.mock()))
• @SafeDIConfiguration properties: generateMocks: Bool and mockConditionalCompilation: StaticString?
• @Instantiable parameter: mockAttributes: StaticString for global actor annotations (e.g., @MainActor)
• Per-module mock generation: Each module with SafeDIGenerator plugin generates mocks for its own types. Mock generation defaults to false when no @SafeDIConfiguration exists.

Example project updates

• Example Package Integration: Plugin added to all targets. Mocks generated for all modules.
• ExampleProjectIntegration: #Preview blocks updated to use .mock() with zero manual construction
• ExampleMultiProjectIntegration: Subproject framework target now has SafeDIGenerator plugin and @SafeDIConfiguration for per-module mock generation. #Preview blocks use .mock().
• ExamplePrebuiltPackageIntegration: Plugin added to all targets.

Documentation

• README: @SafeDIConfiguration examples updated with mock properties
• Manual: New "Mock generation" section covering configuration, usage, path enums, mockAttributes, forwarded properties, and multi-module setup

Testing

• 422 tests total (29 mock generation tests + 393 existing)
• 0 uncovered new lines in MockGenerator
• All tests use exact full-output == comparison (no contains assertions)
• Coverage: Instantiator<T> with/without forwarded properties, erasedToConcreteExistential, extension-based types, deep nesting, multiple branches, protocol fulfillment, lazy self-instantiation cycles, default-valued arguments, conditional compilation variations, and more

Test plan

• 422 tests pass (swift test)
• 0 uncovered new lines (swift test --enable-code-coverage)
• Example Package Integration builds (swift build)
• ExampleProjectIntegration builds (xcrun xcodebuild)
• ExampleMultiProjectIntegration builds (xcrun xcodebuild)
• Lint clean (swiftformat)
• CI passes

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.93%. Comparing base (8a8c8e1) to head (5f7caf4).

Additional details and impacted files

@@                  Coverage Diff                  @@
##           dfed/root-scanner     #204      +/-   ##
=====================================================
+ Coverage              99.92%   99.93%   +0.01%     
=====================================================
  Files                     40       41       +1     
  Lines                   3838     4440     +602     
=====================================================
+ Hits                    3835     4437     +602     
  Misses                     3        3              

Files with missing lines	Coverage Δ
...ICore/Errors/FixableSafeDIConfigurationError.swift	100.00% <100.00%> (ø)
...eDICore/Extensions/AttributeSyntaxExtensions.swift	100.00% <100.00%> (ø)
...afeDICore/Generators/DependencyTreeGenerator.swift	100.00% <100.00%> (ø)
Sources/SafeDICore/Generators/MockGenerator.swift	100.00% <100.00%> (ø)
Sources/SafeDICore/Models/InstantiableStruct.swift	100.00% <100.00%> (ø)
...ources/SafeDICore/Models/SafeDIConfiguration.swift	100.00% <100.00%> (ø)
Sources/SafeDICore/Models/SafeDIToolManifest.swift	100.00% <100.00%> (ø)
...rces/SafeDICore/Visitors/InstantiableVisitor.swift	100.00% <100.00%> (ø)
...feDICore/Visitors/SafeDIConfigurationVisitor.swift	100.00% <100.00%> (ø)
...ources/SafeDIMacros/Macros/InstantiableMacro.swift	100.00% <100.00%> (ø)
... and 3 more

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