Replace main documentation with APP-2026-09-19

The specification of 2026-09-19 fully replaces the previous contest baseline. Adds source DOCX/GeoJSON, current schemas, rules, 32+4 acceptance matrix and migration plan; marks historical documents superseded. Fixes audit A1-A3 through complete source-bound rule validation, all object-type schema cases and generated Markdown. Blocks legacy contest acceptance until runtime migration. Validation: 972 documentation checks, 15 audit regression tests including all 12 corruptions, 89 CI tests. No Java solver or prior development-branch chain is included; product acceptance remains false.