chore(backend): add explicit test data seed command

scripts/seed-testdata.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
+
+cd "$REPO_ROOT"
+
+export ASPNETCORE_ENVIRONMENT="${ASPNETCORE_ENVIRONMENT:-Development}"
+
+if [[ "$ASPNETCORE_ENVIRONMENT" == "Production" && "${CONFIRM_PRODUCTION_SEED:-}" != "true" ]]; then
+  echo "Refusing to seed test data in Production without CONFIRM_PRODUCTION_SEED=true." >&2
+  exit 2
+fi
+
+dotnet run \
+  --no-launch-profile \
+  --project backend/src/Socialize.Api/Socialize.Api.csproj \
+  -- seed-testdata "$@"