refactor(airport): add #[Scope] methods + #[ObservedBy] modernization

- Scopes: active(), byHub(), orderByIcao() — all using #[Scope] attribute
- Attach #[ObservedBy(AirportObserver::class)], remove imperative
  Airport::observe() from ObserverServiceProviders
- Override resolveRouteBinding() for case-insensitive ICAO route binding
  (URLs like /api/airports/kjfk now resolve correctly)
- Drop dead public static array $rules (Prettus validator hook,
  never activated)

app/Models/Airport.php

@@ -3,8 +3,12 @@
 namespace App\Models;
 
 use App\Contracts\Model;
+use App\Models\Observers\AirportObserver;
 use App\Models\Traits\ExpensableTrait;
 use App\Models\Traits\FilesTrait;
+use Illuminate\Database\Eloquent\Attributes\ObservedBy;
+use Illuminate\Database\Eloquent\Attributes\Scope;
+use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
@@ -86,6 +90,7 @@ use Spatie\Activitylog\Traits\LogsActivity;
  *
  * @mixin \Eloquent
  */
+#[ObservedBy(AirportObserver::class)]
 class Airport extends Model
 {
     use ExpensableTrait;
@@ -124,25 +129,6 @@ class Airport extends Model
         'notes',
     ];
 
-    /**
-     * Validation rules
-     */
-    public static array $rules = [
-        'icao'                 => 'required',
-        'iata'                 => 'sometimes|nullable',
-        'name'                 => 'required',
-        'location'             => 'sometimes',
-        'region'               => 'sometimes',
-        'country'              => 'sometimes',
-        'lat'                  => 'required|numeric',
-        'lon'                  => 'required|numeric',
-        'elevation'            => 'nullable|numeric',
-        'ground_handling_cost' => 'nullable|numeric',
-        'fuel_100ll_cost'      => 'nullable|numeric',
-        'fuel_jeta_cost'       => 'nullable|numeric',
-        'fuel_mogas_cost'      => 'nullable|numeric',
-    ];
-
     public $sortable = [
         'id',
         'iata',
@@ -255,6 +241,49 @@ class Airport extends Model
         return $this->hasMany(User::class, 'home_airport_id');
     }
 
+    /**
+     * Marker scope. Airport has no `status`/`active` column, so this is
+     * equivalent to the SoftDeletes default (excludes trashed).
+     *
+     * Reserved for cross-model consistency — Phase 4 (User domain) and
+     * Phase 6 (Flight domain) will add `active()` scopes to `User`,
+     * `Airline`, and other models, at which point reading
+     * `Airport::active()` will match the convention naturally.
+     */
+    #[Scope]
+    protected function active(Builder $q): Builder
+    {
+        return $q->whereNull('deleted_at');
+    }
+
+    /**
+     * Filter to hub airports only.
+     */
+    #[Scope]
+    protected function byHub(Builder $q): Builder
+    {
+        return $q->where('hub', true);
+    }
+
+    /**
+     * Order results by ICAO ascending.
+     */
+    #[Scope]
+    protected function orderByIcao(Builder $q): Builder
+    {
+        return $q->orderBy('icao', 'asc');
+    }
+
+    /**
+     * URLs typically use a lowercase ICAO (e.g. /api/airports/kjfk) but
+     * the table stores ICAO uppercased. Override the default Eloquent
+     * route binding so case-insensitive lookups resolve correctly.
+     */
+    public function resolveRouteBinding($value, $field = null): ?\Illuminate\Database\Eloquent\Model
+    {
+        return $this->resolveRouteBindingQuery($this, strtoupper((string) $value), $field)->first();
+    }
+
     protected function casts(): array
     {
         return [

app/Providers/ObserverServiceProviders.php

@@ -2,13 +2,11 @@
 
 namespace App\Providers;
 
-use App\Models\Airport;
 use App\Models\Flight;
 use App\Models\FlightField;
 use App\Models\FlightFieldValue;
 use App\Models\Journal;
 use App\Models\JournalTransaction;
-use App\Models\Observers\AirportObserver;
 use App\Models\Observers\FlightObserver;
 use App\Models\Observers\JournalObserver;
 use App\Models\Observers\JournalTransactionObserver;
@@ -26,7 +24,6 @@ class ObserverServiceProviders extends ServiceProvider
 {
     public function boot(): void
     {
-        Airport::observe(AirportObserver::class);
         Journal::observe(JournalObserver::class);
         JournalTransaction::observe(JournalTransactionObserver::class);
 

tests/Unit/Models/AirportScopesTest.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Models\Airport;
+
+test('Airport::byHub returns only hubs', function () {
+    Airport::factory()->count(3)->create(['hub' => false]);
+    Airport::factory()->create(['hub' => true, 'icao' => 'KORD']);
+
+    $results = Airport::byHub()->get();
+
+    expect($results->pluck('icao')->all())->toBe(['KORD']);
+});
+
+test('Airport::orderByIcao returns rows in ascending icao order', function () {
+    foreach (['KZZZ', 'KAAA', 'KMMM'] as $icao) {
+        Airport::factory()->create(['id' => $icao, 'icao' => $icao]);
+    }
+
+    $results = Airport::orderByIcao()->get();
+
+    expect($results->pluck('icao')->all())->toBe(['KAAA', 'KMMM', 'KZZZ']);
+});
+
+test('Airport::active excludes soft-deleted airports', function () {
+    Airport::factory()->create(['icao' => 'KAAA']);
+    $trashed = Airport::factory()->create(['icao' => 'KBBB']);
+    $trashed->delete();
+
+    $results = Airport::active()->get();
+
+    expect($results->pluck('icao')->all())->toBe(['KAAA']);
+});
+
+test('Airport scopes compose with each other', function () {
+    Airport::factory()->create(['icao' => 'KZZZ', 'hub' => true]);
+    Airport::factory()->create(['icao' => 'KAAA', 'hub' => true]);
+    Airport::factory()->create(['icao' => 'KMMM', 'hub' => false]);
+
+    $results = Airport::byHub()->orderByIcao()->get();
+
+    expect($results->pluck('icao')->all())->toBe(['KAAA', 'KZZZ']);
+});
+
+test('Airport::resolveRouteBinding upcases the incoming ICAO', function () {
+    Airport::factory()->create(['id' => 'KJFK', 'icao' => 'KJFK']);
+
+    $resolved = (new Airport())->resolveRouteBinding('kjfk');
+
+    expect($resolved)->not->toBeNull()
+        ->and($resolved->id)->toBe('KJFK');
+});
+
+test('Airport::resolveRouteBinding returns null for unknown ICAO', function () {
+    $resolved = (new Airport())->resolveRouteBinding('XXXX');
+
+    expect($resolved)->toBeNull();
+});