feat: add PyFock phase-two optimization and analysis

[NCCU-Schultz-Lab]

Summary

Implements the next PyFock vertical slice for native-Windows quantum chemistry workflows.

• Add PyFock-backed ASE geometry optimization with analytical density-fitted gradients
• Route geometry optimization through the shared engine path
• Preserve MO energies, occupations, coefficients, Mulliken charges, and dipole data
• Add native PyFock orbital-cube generation with basis-coordinate conversion
• Persist engine provenance through optimized results and orbital history
• Add engine-aware teaching/help content and UI analysis routing
• Complete the [pyfock] dependency extra so ASE is installed for optimization

Validated subset

PyFock remains restricted to neutral, closed-shell PBE calculations with def2-SVP or def2-TZVP. Hybrids, charged/open-shell systems, solvent, checkpoint warm starts, and GPU execution remain gated to PySCF.

Validation

• Real PyFock analytical-gradient geometry-wrapper smoke test completed successfully
• Focused regression suite: 496 passed, 1 intentional skip
• Black, Ruff, pre-commit, and whitespace checks passed
• No new private planning locations or repository identifiers are exposed by this change