chore: audit nits — PlanFeatures, test boot, EIA log, static method

Audit items #15, #16, #20, #22.

#15 — AuthController::me and UserResource form/table now read tier via
PlanFeatures::for($user)->tier() instead of Plan::resolveForUser($user)
->name. Tiers.md: PlanFeatures is the single entitlement gate.

#16 — Moved SQLite GREATEST/LEAST PHP-backed function registration from
AppServiceProvider::boot to tests/TestCase::setUp. Production app boot no
longer checks the DB driver name.

#20 — FetchOilPrices: added Log::warning on EIA fallback and Log::error
on both-providers-failed so primary-source reliability can be trended
beyond the cron output buffer.

#22 — FuelPriceService::flattenEnabledFlags is now an instance method,
matching the rest of the class. No external callers.

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

app/Filament/Resources/UserResource.php

@@ -9,6 +9,7 @@ use App\Filament\Resources\UserResource\Pages\EditUser;
 use App\Filament\Resources\UserResource\Pages\ListUsers;
 use App\Models\Plan;
 use App\Models\User;
+use App\Services\PlanFeatures;
 use Filament\Actions\DeleteAction;
 use Filament\Actions\EditAction;
 use Filament\Forms\Components\DateTimePicker;
@@ -75,7 +76,7 @@ class UserResource extends Resource
                     ->live()
                     ->dehydrated(false)
                     ->afterStateHydrated(fn (Select $component, ?User $record) => $component
-                        ->state($record ? Plan::resolveForUser($record)->name : PlanTier::Free->value)),
+                        ->state($record ? PlanFeatures::for($record)->tier() : PlanTier::Free->value)),
                 Select::make('cadence')
                     ->label('Billing Cadence')
                     ->options([
@@ -131,7 +132,7 @@ class UserResource extends Resource
                 TextColumn::make('postcode')->placeholder('—'),
                 TextColumn::make('tier')
                     ->label('Tier')
-                    ->state(fn (User $record): string => Plan::resolveForUser($record)->name)
+                    ->state(fn (User $record): string => PlanFeatures::for($record)->tier())
                     ->badge()
                     ->colors([
                         'gray' => 'free',