CKey Format v0.19.0 — Profile 2 Frame Safety Moat

Profile 2 retains its 29-unit field, RS(255,210) frame, deterministic visual fill, and Grid/Ring/Ray calibration keys. Its payload lattice now reserves a 1.35-unit clear moat around the continuous border. A module that lands in the frame's raster or blur fringe is not an optical data site.

The change is geometric and changes the codeword-to-site mapping. Encoders emit frame format byte 0x13 (decimal 19), profile byte 0x02. A Profile 2 reader must use this site's mapping for format 19; earlier format mappings are historical decode paths only.