CONV-301: Add converter schema endpoint

routes/api.php

@@ -23,5 +23,6 @@
             }
 
             Route::get('/converters', [ConverterController::class, 'index'])->name('converters.index');
+            Route::get('/converters/{source}/{target}/schema', [ConverterController::class, 'schema'])->name('converters.schema');
         });
     });

tests/Feature/Api/V1/ConverterSchemaEndpointTest.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Enums\Plan;
+use App\Models\User;
+use App\Services\Api\ApiKeyGenerator;
+
+it('returns converter options schema for valid pair', function () {
+    $user = User::factory()->create(['plan' => Plan::Pro]);
+    $token = app(ApiKeyGenerator::class)->create($user, 'API')->plainToken;
+
+    $this->withToken($token)
+        ->getJson('/api/v1/converters/png/jpg/schema')
+        ->assertOk()
+        ->assertJsonPath('data.source_format', 'png')
+        ->assertJsonPath('data.target_format', 'jpg')
+        ->assertJsonStructure([
+            'data' => [
+                'source_format',
+                'target_format',
+                'options',
+            ],
+        ]);
+});
+
+it('returns 422 for unsupported conversion pair', function () {
+    $user = User::factory()->create(['plan' => Plan::Pro]);
+    $token = app(ApiKeyGenerator::class)->create($user, 'API')->plainToken;
+
+    $this->withToken($token)
+        ->getJson('/api/v1/converters/png/mp3/schema')
+        ->assertStatus(422)
+        ->assertJsonPath('error.code', 'unsupported_conversion');
+});
+
+it('requires api key authentication to get converter schema', function () {
+    $this->getJson('/api/v1/converters/png/jpg/schema')
+        ->assertUnauthorized();
+});