feat(form-builder): form_field_conditional_logic_{groups,conditions} tables + OrganisationScope cap raise to 5

WS-5c commit 1 of 4 — relational infrastructure for the conditional-
logic tree that replaces form_fields.conditional_logic JSON (ARCH-
FORM-BUILDER §8; addendum Q3 WS-5c).

Tables: groups (nesting via parent_group_id) + conditions (leaves,
value JSON nullable for empty/not_empty). Simple FK to form_fields —
addendum Q3 explicitly excludes form_field_library from conditional_
logic scope, so no polymorphic morph here.

OrganisationScope cap raised 3 → 5 hops. The conditions chain is
4 hops (condition → group → field → schema → organisation_id column)
and the new cap gives headroom for future deeper trees without
denormalising form_field_id onto conditions.

Cascade observer (FormFieldChildTablesCascadeObserver) extended to
physically delete the new groups table on FormField delete (hard or
soft). Conditions cascade automatically via the group_id FK on the
groups table.

Factories: FormFieldConditionalLogicGroupFactory, FormFieldConditional
LogicConditionFactory, and FormFieldFactory::withConditionalLogic($tree)
for concise test fixtures.

Tests: 16 new under tests/Feature/FormBuilder/ConditionalLogic/
(relation, scope, cascade, enum catalogue). 3 new scope-cap tests in
ScopeLeakageTest verify 4/5-hop chains pass and 6-hop throws. Hardcoded
rollback step counts in WS-5a/b migration tests bumped for the 2 new
WS-5c migrations. Baseline 1104 → 1122 green (2988 → 3032 assertions).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/database/migrations/2026_04_26_100000_create_form_field_conditional_logic_groups_table.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * WS-5c commit 1 of 4 — tree root/branch for relational conditional logic
+ * that replaces `form_fields.conditional_logic` JSON (ARCH-FORM-BUILDER §8;
+ * ARCH-CONSOLIDATION-ADDENDUM-2026-04-24 §Q3).
+ *
+ * Simple FK to `form_fields` — per addendum Q3 the library is explicitly
+ * out of scope for conditional_logic. No polymorphic owner here. Groups
+ * nest via `parent_group_id` (null at the root); leaves live in the
+ * sibling `form_field_conditional_logic_conditions` table.
+ *
+ * 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_conditional_logic_groups', function (Blueprint $table) {
+            $table->ulid('id')->primary();
+            $table->foreignUlid('form_field_id')
+                ->constrained('form_fields')
+                ->cascadeOnDelete();
+            $table->foreignUlid('parent_group_id')
+                ->nullable()
+                ->constrained('form_field_conditional_logic_groups')
+                ->cascadeOnDelete();
+            $table->string('operator', 10);
+            $table->unsignedInteger('sort_order')->default(0);
+            $table->timestamps();
+
+            $table->index('form_field_id', 'ffclg_field_idx');
+            $table->index(['parent_group_id', 'sort_order'], 'ffclg_parent_sort_idx');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('form_field_conditional_logic_groups');
+    }
+};

api/database/migrations/2026_04_26_100001_create_form_field_conditional_logic_conditions_table.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * WS-5c commit 1 of 4 — leaves of the relational conditional-logic tree.
+ * Each row holds one `(field_slug, comparison_operator, value)` condition
+ * that belongs to a parent group. Conditions and sub-groups are siblings
+ * under a group; their mixed ordering is preserved via `sort_order`, read
+ * back by `FormFieldConditionalLogicService::toJsonShape`.
+ *
+ * `value` is JSON nullable — scalar for most operators, array for in/
+ * not_in, null for empty/not_empty. Shape is validated at the service
+ * layer, not the DB (ARCH-FORM-BUILDER §8).
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('form_field_conditional_logic_conditions', function (Blueprint $table) {
+            $table->ulid('id')->primary();
+            $table->foreignUlid('group_id')
+                ->constrained('form_field_conditional_logic_groups')
+                ->cascadeOnDelete();
+            $table->string('field_slug', 100);
+            $table->string('comparison_operator', 20);
+            $table->json('value')->nullable();
+            $table->unsignedInteger('sort_order')->default(0);
+            $table->timestamps();
+
+            $table->index(['group_id', 'sort_order'], 'ffclc_group_sort_idx');
+            $table->index('field_slug', 'ffclc_field_slug_idx');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('form_field_conditional_logic_conditions');
+    }
+};