Sector atlas, masses, nuclei

With the sector grammar and generation topology in place, the particle atlas is read as a classification of carrier modes. Mass ratios and Koide-type relations are character-mode / generation-geometry readouts; hadrons are confined composites and toroidal saturation regimes; nuclei are defect-stacking regimes with shell-model emergence. This step does not derive all nuclear physics in the main text. It records the construction role: the same defect/holonomy grammar that defined particles now organizes composite matter.