Minimize demo-data technical debt fleet-wide

Elazar directive (2026-07-17, via coder-pluto-cc). Demo/seed data was meant as throwaway (client pre-launch testing, delete before go-live) but became a permanent DB-model concern: isDemo=false (+ per-app equivalents) gates scattered across code, demo periodo/comisiones/user seed rows living in prod. Elazar position: this data will NEVER be created again, so every gate/branch carrying it is pure debt. Active cost example: PLUTO-578 - demo seed uuids (c0000000-...-000N, migrations 032/034/038/042) have RFC4122-noncompliant version/variant nibbles; a too-strict isUuid validator false-negated them and 404'd every seeded [id] detail route; Elazar hit it clicking comisiones (fixed abc35a0/v2.16.24, but symptom of larger debt). SCOPE (design/scoping, PM-owned, dispatch per app): per app - (1) inventory every isDemo/demo-* gate + demo seed rows, (2) decide purge-vs-keep per app (archive-context aware for trigger-archived tables = db-lane work; setArchiveContext before delete), (3) remove now-dead gates once rows purged. Per-app subtasks track execution.