feat(db): Bun.SQL connection and portable migrations

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/test-pg.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+# Runs the package tests against SQLite and a throwaway postgres:17 container.
+set -euo pipefail
+PORT="${STC_PG_PORT:-55432}"
+cd "$(dirname "$0")/.."
+trap 'docker stop stc-pg >/dev/null 2>&1 || true' EXIT
+docker rm -f stc-pg >/dev/null 2>&1 || true
+docker run -d --rm --name stc-pg -e POSTGRES_PASSWORD=stc -p 127.0.0.1:${PORT}:5432 postgres:17 >/dev/null
+for _ in $(seq 1 60); do
+  docker exec stc-pg pg_isready -U postgres -h 127.0.0.1 >/dev/null 2>&1 && break
+  sleep 1
+done
+sleep 1
+STC_TEST_PG_URL="postgres://postgres:stc@127.0.0.1:${PORT}/postgres" bun test packages