mol3d.js scene-owned orbital overlays

This patch is rebased directly on v16.0.1. The older v15.4.1 overlay ZIP should not be deployed over v16 because /api/model now gets its orbitals from qo_chem.

3Dmol owns the molecular coordinates R, bonds and camera. qo_chem owns orbital coefficients and chemistry. mol3d.js is the read-only scene adapter.

For each local orbital:

psi_i(r) = F_i(r - R_i; O_i)

R_i is read from the loaded 3Dmol model; O_i comes from /api/model. Orbital patches may be created and removed, but they do not write to R_i.

The viewer shows the maximum API/3Dmol coordinate discrepancy as a diagnostic. It still uses the 3Dmol coordinate even when that diagnostic fails.

The separately uploaded radial experiment was checked against v16.0.1; all nine files are byte-for-byte identical to tools/radial/ in the base archive.