feat(db): add rent_payment_destinations column and multi-schema support

- Add migration 0020 for rent_payment_destinations jsonb column
- Add DB_SCHEMA env var support for multi-schema deployments
- Create custom migrate.ts script with proper search_path handling
- Update drizzle.config.ts and client.ts to use DB_SCHEMA
- Add db_schema variable to Terraform with dev=test/prod=public defaults
- Update CD workflow to set DB_SCHEMA based on branch

infra/terraform/variables.tf

@@ -259,3 +259,9 @@ variable "github_deploy_service_account_id" {
   type        = string
   default     = "github-deployer"
 }
+
+variable "db_schema" {
+  description = "Database schema name for the application"
+  type        = string
+  default     = "public"
+}