18b1e0f66e
The .picpeak restore suites gate their Postgres cases behind PICPEAK_PG_TEST_URL and describe.skip themselves out when it is unset. That variable was set in no workflow, so those cases have never run in CI — the suites reported green while silently skipping the half that needs a real database: sequence resync, operator/role preservation across a cross-instance restore, and whether a coerced row lands with the right STORED VALUES rather than merely not throwing. Add a postgres:15-alpine service to the backend job (same shape schema-drift already uses) and point the variable at it. Everything else in the suite still runs on SQLite; this only un-gates the cases that were skipping. Verified against a real Postgres 15 before wiring: picpeakRestorePg 4/4 and picpeakCrossEngine 11/11 (8 of which were previously skipped across both). Matters now because #1043 opens sqlite -> pg restore to the upload UI, so the coercion layer's correctness stops being a CLI-only concern. Co-authored-by: Paul Nothaft <paul@MacStudio-von-Paul.local>