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

tests/Feature/Payments/AssignTierFromEditPageTest.php

@@ -0,0 +1,66 @@
+<?php
+
+use App\Filament\Resources\UserResource\Pages\EditUser;
+use App\Models\Plan;
+use App\Models\User;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Livewire\Livewire;
+
+uses(RefreshDatabase::class);
+
+beforeEach(function (): void {
+    $this->artisan('db:seed', ['--class' => 'PlanSeeder']);
+    $admin = User::factory()->create(['is_admin' => true]);
+    $this->actingAs($admin);
+});
+
+it('creates an admin-granted subscription when a paid tier is chosen', function (): void {
+    $user = User::factory()->create();
+
+    Livewire::test(EditUser::class, ['record' => $user->id])
+        ->fillForm(['tier' => 'basic', 'cadence' => 'monthly'])
+        ->call('save')
+        ->assertHasNoFormErrors();
+
+    $subscription = $user->subscriptions()->first();
+    expect($user->subscriptions()->count())->toBe(1)
+        ->and($subscription->stripe_id)->toStartWith('admin_')
+        ->and($subscription->stripe_status)->toBe('active')
+        ->and(Plan::resolveForUser($user->fresh())->name)->toBe('basic');
+});
+
+it('removes any admin-granted subscription when tier is set to free', function (): void {
+    $user = User::factory()->create();
+
+    Livewire::test(EditUser::class, ['record' => $user->id])
+        ->fillForm(['tier' => 'basic', 'cadence' => 'monthly'])
+        ->call('save');
+    expect($user->subscriptions()->count())->toBe(1);
+
+    Livewire::test(EditUser::class, ['record' => $user->fresh()->id])
+        ->fillForm(['tier' => 'free'])
+        ->call('save');
+
+    expect($user->subscriptions()->count())->toBe(0)
+        ->and(Plan::resolveForUser($user->fresh())->name)->toBe('free');
+});
+
+it('refuses to change tier when the user has a real Stripe subscription', function (): void {
+    $user = User::factory()->create();
+
+    $user->subscriptions()->create([
+        'type' => 'default',
+        'stripe_id' => 'sub_real_stripe_id',
+        'stripe_status' => 'active',
+        'stripe_price' => 'price_plus_monthly',
+        'quantity' => 1,
+    ]);
+
+    Livewire::test(EditUser::class, ['record' => $user->id])
+        ->fillForm(['tier' => 'pro', 'cadence' => 'monthly'])
+        ->call('save');
+
+    $adminCount = $user->subscriptions()->where('stripe_id', 'like', 'admin_%')->count();
+    expect($adminCount)->toBe(0)
+        ->and($user->subscriptions()->count())->toBe(1);
+});