feat: add searches table, model, and factory for API search logging

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

database/migrations/2026_04_04_180819_create_searches_table.php

@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('searches', function (Blueprint $table): void {
+            $table->bigIncrements('id');
+            $table->decimal('lat_bucket', 5, 2)->comment('Latitude rounded to 2dp (~1km precision) for privacy');
+            $table->decimal('lng_bucket', 5, 2)->comment('Longitude rounded to 2dp for privacy');
+            $table->string('fuel_type', 20);
+            $table->unsignedSmallInteger('results_count');
+            $table->unsignedSmallInteger('lowest_pence')->nullable()->comment('Cheapest price found in pence × 100');
+            $table->unsignedSmallInteger('highest_pence')->nullable()->comment('Most expensive price found in pence × 100');
+            $table->decimal('avg_pence', 8, 2)->nullable()->comment('Mean price across results in pence × 100');
+            $table->dateTime('searched_at');
+            $table->string('ip_hash', 64)->comment('SHA-256 of requester IP — non-reversible, for unique count only');
+
+            $table->index(['searched_at', 'fuel_type']);
+            $table->index('ip_hash');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('searches');
+    }
+};