MonomialMemorySpace release-all methods leave the allocation count stale

Both freeAllAllocs and freeAllAllocsAndBackingMemory in M2/Macaulay2/e/monomials/monomial-sets.hpp release storage but do not reset mCount.

MonomialMemorySpace arena;
arena.allocate(3);
arena.allocate(5);
arena.freeAllAllocs(); // same result with freeAllAllocsAndBackingMemory()
// expected arena.size() == 0; actual 2
auto* next = arena.allocate(2);
// expected size 1; actual 3
arena.popLastAlloc(next);
// expected size 0; actual 2

The normal allocate/pop path uses this count as the live allocation count, and owning monomial collections use it as their size.

Reproduced for both release methods in direct Debug engine tests at c156fdcba4 (Apple Clang 21). No production changes.

Failing unit-test blocks

• TEST(MonomialCollections, DISABLED_releaseAllResetsLiveCount) in M2/Macaulay2/e/unit-tests/MonomialCollectionsTest.cpp.

These regressions were explicitly run and confirmed to fail against the current implementation. They assert the intended corrected behavior and remain disabled in normal runs until the defect is fixed.

Run from the CMake build directory after building M2-unit-tests:

./Macaulay2/e/M2-unit-tests \
  --gtest_also_run_disabled_tests \
  --gtest_filter='MonomialCollections.DISABLED_releaseAllResetsLiveCount'

Start in M2/Macaulay2/e/monomials/monomial-sets.hpp and inspect freeAllAllocs and freeAllAllocsAndBackingMemory, then read the disabled test in M2/Macaulay2/e/unit-tests/MonomialCollectionsTest.cpp. Run the specified M2-unit-tests command from the CMake build directory. Done means both release methods leave size() at zero and the subsequent allocate/pop sequence reports the correct live count.