Use HayWadt ECP for ORCA LANL2DZ

[oiahoon]

Summary

• map the Basis Set Exchange LANL2DZ ECP name to ORCA's HayWadt ECP keyword
• add an ORCA regression test using the existing AuI structure

Why

When LANL2DZ is assigned as a custom basis set for a heavy atom, Basis Set Exchange identifies the matching ECP as LANL2DZ ECP. The generic name mapping produced LANL2DZECP, which ORCA does not recognize. ORCA documents HayWadt as the ECP associated with LANL2DZ.

The mapping is ORCA-specific, so other package names are unchanged.

Closes #13.

Validation

• reproduced the original CLI output with NewECP Au "LANL2DZECP" end
• verified the corrected CLI output uses NewECP Au "HayWadt" end
• focused regression test: 1 passed
• complete ORCA tests: 72 passed
• non-CLI test suite: 448 passed
• Black check for both changed files
• Python compileall and Git diff checks

The complete 514-test run passed 490 tests. The remaining 24 pre-existing CLI failures occur because those tests construct unquoted command strings and the local checkout path contains a space; the same 24 failures were present before this change.

[RaphaelRobidas]

Hello, thanks for the PR.

Did you validate that the reference output file used in your test works? Iodine normally should have an ECP as well. Also, the test failures you mention seem to be specific to your local path, which contains a space. On my end, I don't have a space in the path and all tests pass. If you could suggest a fix for that issue, it would be great.

[oiahoon]

Addressed in bf3909c. The regression now assigns I=Def2-TZVPD and verifies NewECP I "def2-ECP", so both Au and I have explicit matching basis/ECP entries.

I validated the generated input against the ORCA 6.1 basis/ECP documentation and Basis Set Exchange metadata. ORCA is not installed locally, so I did not run an actual calculation. In the clean checkout without spaces, the full suite passes 514/514.

For the path-space failures, the likely test-harness fix is to shell-quote the interpolated fixture paths before shlex.split() (or pass argument lists directly). I kept that broader test-only cleanup separate from this LANL2DZ change.