fix: preserve HR data when wrapping HContainer with external data_array

[dyzheng]

The HContainer copy constructor was unconditionally zeroing out the data_array when wrapping existing memory. This caused getHR_vector() to erase both spin channels' HR data for nspin=2, resulting in all-zero HR output when out_mat_hs2 is enabled.

Fix: only zero memory when data_array is nullptr (fresh allocation); preserve existing data when wrapping external memory.

Also add integration test scf_out_hsr_spin2 (nspin=2 + out_mat_hs2) and update catch_properties.sh to compare hrs2_nao.csr for nspin=2.

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Linked Issue

Fix #7535

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[mohanchen]

LGTM