many fixes and improvements - rework for modules/ and common/

feat(emailer): add Postmark and Resend providers

backend/scripts/add-migration.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# Usage: ./add-migration.sh Messaging Initial
+
+MODULE_NAME=$1
+MIGRATION_NAME=$2
+
+if [ -z "$MODULE_NAME" ] || [ -z "$MIGRATION_NAME" ]; then
+  echo "Usage: $0 <ModuleName> <MigrationName>"
+  exit 1
+fi
+
+dotnet ef migrations add \
+  --context "Hutopy.Modules.${MODULE_NAME}.Data.${MODULE_NAME}DbContext" \
+  --configuration Debug \
+  --output-dir "Modules/${MODULE_NAME}/Migrations" \
+  "$MIGRATION_NAME"