Updated ASET

[wateriousmelon2333]

1. Fixed ASET bug, now fragment allows atoms with more than 1 letter.
2. Updated ASET so it can run on AVAS projected orbitals, prior to CASSCF.
3. Updated McOptimizer so mix_inactive is false when parent method is ASET.
4. Added one test case.

[Copilot]

Pull Request Overview

This PR updates the ASET (Active Space Embedding Theory) implementation to support multi-letter atomic symbols, enable execution on AVAS-projected orbitals, and improve orbital optimization behavior. The key changes include:

• Fixed regex pattern to properly handle atoms with 1-2 letter symbols (e.g., "Li", "Cl")
• Extended ASET to accept AVAS as a parent method in addition to MCOptimizer
• Updated MCOptimizer to disable inactive orbital mixing when parent method is ASET
• Added test case demonstrating the AVAS→ASET→CASSCF workflow

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 3 comments.

File	Description
tests/orbitals/test_aset.py	Added AVAS import and new test case for AVAS→ASET→CASSCF workflow
tests/orbitals/reference_aset_orbitals/test_aset_6_orbitals.npy	Reference orbital data for new test case
forte2/orbitals/aset.py	Updated fragment parsing regex, added AVAS support, new compute_g1_sf method, removed unused import
forte2/mcopt/mc_optimizer.py	Added ASET import, conditional mix_inactive logic, fixed typo in comment

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[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.98%. Comparing base (6446c7d) to head (47af70e).

Files with missing lines	Patch %	Lines
forte2/orbitals/aset.py	72.22%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #122      +/-   ##
==========================================
- Coverage   94.08%   92.98%   -1.10%     
==========================================
  Files         150      150              
  Lines       12988    13006      +18     
  Branches     1008     1011       +3     
==========================================
- Hits        12220    12094     -126     
- Misses        534      676     +142     
- Partials      234      236       +2     

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