feat(template): per-experiment daily record template — rename/add/hide fields, custom_fields JSONB

backend/prisma/migrations/20240102000000_add_template_and_custom_fields/migration.sql

@@ -0,0 +1,5 @@
+-- Add template field to experiments (JSON array of field definitions)
+ALTER TABLE "experiments" ADD COLUMN "template" JSONB NOT NULL DEFAULT '[]';
+
+-- Add custom_fields to daily_statuses (stores values for non-builtin fields)
+ALTER TABLE "daily_statuses" ADD COLUMN "custom_fields" JSONB;