Function test_container_capacity_management

tests/test_container_helpers.h:664–681

// Test capacity management for heap-based containers
template<typename Container>
void test_container_capacity_management() {
    Container c;

    // Test initial capacity - COMPILER ERROR if capacity() doesn't exist
    FL_CHECK(c.capacity() >= 0);

    // Test reserve - COMPILER ERROR if reserve() doesn't exist
    c.reserve(100);
    FL_CHECK(c.capacity() >= 100);
    FL_CHECK(c.size() == 0);  // Size unchanged

    // Populate without reallocation
    for (int i = 0; i < 50; ++i) {
        populate(c, make_shared_int(i));
    }
    FL_CHECK(c.size() == 50);
    FL_CHECK(c.capacity() >= 100);
}

// Test shrink_to_fit for heap-based containers
template<typename Container>