Remove unreachable classes before compiler lowering

[Frotty]

Unused classes survive the early tree shaker and are processed by compile-time passes, generic specialization, and Jass class lowering. Remove classes whose types, surviving implementations, fields, and inheritance relationships are unreachable, collecting dependencies during the existing function walk rather than traversing function bodies again.

Keep the class universe when reachable reflection or explicit type-ID reads expose its numbering, including reads consumed at compile time. Preserve compile-time allocator state, Jass inheritance joins that share an allocator, and Lua nominal identities for targeted specializations. Record generic static-field ownership during class translation so specialization cannot lose classes used without an instance. Remove the completed class-pruning item from the backlog.

Validation:

• New class-retention regressions failed before implementation and now pass.
• 703 tests across TreeShakerTests, DeterministicChecks, GenericsTests, GenericsWithTypeclassesTests, FieldIterationTests, CompiletimeTests, NewFeatureTests, LuaTranslationTests, ClassesTests, and ClosureTests passed with no skips, including Jass/Lua execution and shuffled-unit output checks.
• Local castle-fight measurement: 3,596 classes become 2,137 before compile-time processing on both targets (1,459 removed, about 41%). Timing samples were mixed; this does not claim an end-to-end build-time speedup.
• git diff --check passed. The full test suite remains for PR CI.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-14T06:52:24.242807Z	3757b4a	PR opened

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