Add tier feature design spec, annual billing, fuel type normalization, and admin subscription management

- Add comprehensive tier feature matrix spec defining Free/Basic/Plus/Pro capabilities across recommendations, predictions, history, logs, tools, and family sharing
- Add `stripe_price_id_annual` column to plans table and rename existing column to `stripe_price_id_monthly`
- Normalize legacy fuel type aliases (petrol→e10, diesel→b7_standard) in users table
- Implement BillingController with checkout, portal, success/cancel routes supporting monthly/annual cadence
- Add admin subscription assignment in Filament user edit page with admin-granted subscription support
- Add DowngradeUserOnSubscriptionDeleted listener to disable WhatsApp/SMS preferences on subscription cancellation
- Add MissedNotificationsOverview widget to Filament user detail page
- Add PollFuelPricesTest covering auto-refresh scenarios
- Add PriceReliability enum with reliability classification based on price age
- Add fuelTypes.js constants file exporting FUEL_TYPES from window global

database/migrations/2026_04_14_182632_add_annual_stripe_price_id_to_plans_table.php

@@ -0,0 +1,31 @@
+<?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::table('plans', function (Blueprint $table) {
+            $table->renameColumn('stripe_price_id', 'stripe_price_id_monthly');
+        });
+
+        Schema::table('plans', function (Blueprint $table) {
+            $table->string('stripe_price_id_annual')->nullable()->after('stripe_price_id_monthly')
+                ->comment('Cashier price ID for annual billing');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('plans', function (Blueprint $table) {
+            $table->dropColumn('stripe_price_id_annual');
+        });
+
+        Schema::table('plans', function (Blueprint $table) {
+            $table->renameColumn('stripe_price_id_monthly', 'stripe_price_id');
+        });
+    }
+};

database/migrations/2026_04_14_213226_normalize_preferred_fuel_type_aliases.php

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+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        $map = [
+            'petrol' => 'e10',
+            'unleaded' => 'e10',
+            'premium_unleaded' => 'e5',
+            'diesel' => 'b7_standard',
+            'premium_diesel' => 'b7_premium',
+        ];
+
+        foreach ($map as $from => $to) {
+            DB::table('users')->where('preferred_fuel_type', $from)->update(['preferred_fuel_type' => $to]);
+        }
+
+        Schema::table('users', function (Blueprint $table) {
+            $table->string('preferred_fuel_type', 20)->default('e10')->change();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->string('preferred_fuel_type', 20)->default('petrol')->change();
+        });
+
+        DB::table('users')->where('preferred_fuel_type', 'e10')->update(['preferred_fuel_type' => 'petrol']);
+        DB::table('users')->where('preferred_fuel_type', 'b7_standard')->update(['preferred_fuel_type' => 'diesel']);
+    }
+};