[wsttiger]

The release needs a runnable example of quantum data selecting fermionic basis changes and orbital reflections. This adds the canonical fermion_basis_change.py tutorial: fixed and externally controlled transformations, full QROM selection, partial selected reflections, and three/four-bit off-grid precision checks.

The full fixed/control/QROM fixture and initial chemistry pages are adapted from PR #78 at 6f542f1. This PR targets main independently and includes those still-unmerged pages; it neither stacks on #78 nor depends on any other release-example PR.

Validation on Python 3.12.3 / CUDA-Q 0.16.0.post1, fp64 qpp-cpu:

• Standalone example: 6.14 s; represented-operator/full-state errors approximately 1e-15, including angle/ladder cleanup and coherent controls.
• test_examples.py -k fermion_basis_change: 1 passed, 18 deselected (6.26 s).
• Sphinx with -W and YAPF 0.43.0: pass.
• Full transform: 16 qubits. Partial programs: 13/16 qubits at b=3/4, plus one external enable when used.
• Off-grid reflection errors: 0.640050 at b=3 and 0.203412 at b=4, below the separate public bounds 0.981593 and 0.505398. Circuit tolerances remain 1e-10; original fixed checks retain 1e-12.

Documentation includes register conventions, paper citations, and scope: this isolates programmable orbital actions rather than reproducing the complete chemistry algorithms or their fault-tolerant costs. No library or dependency changes.