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/app/Models/FormBuilder/FormFieldConditionalLogicCondition.php

@@ -0,0 +1,64 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models\FormBuilder;
+
+use App\Enums\FormBuilder\FormFieldConditionalLogicConditionOperator;
+use App\Models\Scopes\OrganisationScope;
+use Illuminate\Database\Eloquent\Concerns\HasUlids;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+/**
+ * A leaf of the relational conditional-logic tree — one comparison
+ * of `(field_slug, operator, value)` against the current form values
+ * (ARCH-FORM-BUILDER §8).
+ *
+ * `value` is JSON nullable: scalar for most operators, array for
+ * `in`/`not_in`, null for `empty`/`not_empty`. Shape validation is
+ * enforced at the service layer (`FormFieldConditionalLogicService
+ * ::assertSpecsValid`), not the DB.
+ *
+ * Multi-tenancy chain is 4 hops (condition → group → field → schema →
+ * organisation_id column) — inside the WS-5c raised cap of 5.
+ */
+final class FormFieldConditionalLogicCondition extends Model
+{
+    use HasFactory;
+    use HasUlids;
+
+    protected $table = 'form_field_conditional_logic_conditions';
+
+    protected static function booted(): void
+    {
+        static::addGlobalScope(new OrganisationScope());
+    }
+
+    /** @return array{via: class-string, fk: string} */
+    public static function tenantScopeStrategy(): array
+    {
+        return ['via' => FormFieldConditionalLogicGroup::class, 'fk' => 'group_id'];
+    }
+
+    protected $fillable = [
+        'group_id',
+        'field_slug',
+        'comparison_operator',
+        'value',
+        'sort_order',
+    ];
+
+    /** @var array<string, string> */
+    protected $casts = [
+        'comparison_operator' => FormFieldConditionalLogicConditionOperator::class,
+        'value' => 'array',
+        'sort_order' => 'int',
+    ];
+
+    public function group(): BelongsTo
+    {
+        return $this->belongsTo(FormFieldConditionalLogicGroup::class, 'group_id');
+    }
+}