fix: for-of on class array filter/sort/slice results

[cs01]

Summary

• for (const t of arr.filter(...)) on class arrays produced garbage when accessing fields — the element type was lost through the filter/sort/slice/reverse methods
• Root cause: three places needed to propagate the class element type through array-preserving methods:
  1. getObjectArrayElementType (type-inference.ts) — added variable and array literal cases, plus recursive resolution through filter/sort/reverse/slice
  2. getIterableClassElementType (control-flow.ts) — propagate element type through array-preserving method calls
  3. generateGlobalVariableDeclarations (llvm-generator.ts) — use getObjectArrayElementType when resolvedBase is "object" to find the actual class name

Test plan

• New fixture arrays/class-array-for-of-filter.ts — for...of on filter result + sort result
• Index access on filter result still works (done[0].name)
• All existing tests pass
• Self-hosting Stage 1 passes

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