[PurHur]

Summary

• Closes Regression: unset($obj->arr[$k]) no-ops again on instance/static array props — Zend removes (re-#24250, zend_execute.c) #31818 — unset($obj->arr[$k]) / unset(Class::$arr[$k]) / ArrayAccess offsetUnset that unsets a property dim were no-ops again after Language: isset/empty/?? on dim of uninitialized typed property throws Error — Zend BP_VAR_IS (zend_object_handlers.c) #31783 marked those PropertyFetches as propertyHookCoalesceRead (FETCH_OBJ_IS), so the unset mutated a copy.
• Keep FETCH_OBJ_IS / FETCH_STATIC_PROP_IS only for isset/empty/?? dim preludes; unset keeps R-mode live alias (Regression: unset($obj->arr[$k]) no-ops on typed/private instance array props — Zend removes (Zend/zend_execute.c) #24250).
• php-src: Zend/zend_execute.c ZEND_UNSET_DIM; PHP fix in lib/Compiler.php (no new C).

Test plan

• ./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_unset_object_array_dim.php' — empty arrays (matches Zend)
• ./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_unset_object_array_dim_static.php' — t=1 u=1
• ./script/phpunit.sh --filter 'UnsetComplianceTest|TypedPropIssetDimUninit31783VMTest|TypedPropIssetDimUninit31783JITTest|UninitTypedArrayDimAssignVMTest|UninitTypedArrayDimRwVMTest' — OK (12 + 1 JIT)

Verification transcript (VM repro)

t=array (
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pt=array (
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u=array (
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pu=array (
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