feat(plugin-security): the boot writes no sys_position row — delete the built-in and declared position seeders and the everyone baseline junction writer (ADR-0131 D2, #15204 stage 6a)

feat(plugin-security): the boot writes no sys_position row — delete the built-in and declared position seeders and the everyone baseline junction writer (ADR-0131 D2, #15204 stage 6a) #15135