feat(form-builder): form_field_validation_rules table + polymorphic owner + scope + cascade

api/database/migrations/2026_04_25_110000_create_form_field_validation_rules_table.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * WS-5b commit 1 of 5 — relational home for what was `form_fields.validation_rules`
+ * and `form_field_library.validation_rules` JSON. Polymorphic owner (morph
+ * aliases `form_field` and `form_field_library`), one row per
+ * (owner, rule_type) with a typed `rule_type` column and a per-rule
+ * `parameters` JSON bag (ARCH-CONSOLIDATION-ADDENDUM-2026-04-24 §Q3,
+ * ARCH-FORM-BUILDER §17.4).
+ *
+ * This commit is pure infrastructure — no backfill. The legacy JSON bag
+ * is migrated to rows by commit 2's backfill migration so readers and
+ * writers can be switched over as a second atomic step.
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('form_field_validation_rules', function (Blueprint $table) {
+            $table->ulid('id')->primary();
+            $table->string('owner_type', 40);
+            $table->ulid('owner_id');
+            $table->string('rule_type', 40);
+            $table->json('parameters');
+            $table->string('error_message_key', 100)->nullable();
+            $table->timestamps();
+
+            $table->unique(
+                ['owner_type', 'owner_id', 'rule_type'],
+                'ffvr_owner_rule_unique',
+            );
+            $table->index('rule_type', 'ffvr_rule_idx');
+            $table->index(['owner_type', 'owner_id'], 'ffvr_owner_idx');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('form_field_validation_rules');
+    }
+};