Document the xsm modeling language Builds out the wiki from state_model.peg, which stays the ground truth. Structure follows the grammar's own sections rather than mirroring the xcm-parser wiki, since a state model has different concerns: the lifecycle vs assigner choice, events, initial transitions, and the state block with its signature, activity, transitions and deletion marker. The metadata pages are carried over from xcm-parser nearly verbatim, the grammars being all but identical; xsm's resource_item is a single name, so that page is adjusted accordingly. Examples come from the Elevator Management domain in xuml-populate, mostly door.xsm with R53.xsm for the assigner case, referenced by absolute URL. Every grammar excerpt was checked against the .peg verbatim and every snippet shown was run through the parser. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>