refactor(api): validate and throttle feedback endpoint

- Validate content (required string, min:10, max:2000) in OtherController@feedback
- Register 'feedback' named rate limiter (3/min per user or IP) in RouteServiceProvider
- Apply throttle:feedback middleware to POST /api/feedback
- Forward to Discord with allowed_mentions.parse=[] and a 5s HTTP timeout

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/Feature/FeedbackEndpointTest.php

@@ -0,0 +1,96 @@
+<?php
+
+use Illuminate\Support\Facades\Http;
+
+beforeEach(function () {
+    Http::fake([
+        'discord.com/*' => Http::response([], 204),
+    ]);
+});
+
+it('rejects feedback with missing content', function () {
+    $response = $this->postJson('/api/feedback', []);
+
+    $response->assertStatus(422)
+        ->assertJsonValidationErrors('content');
+});
+
+it('rejects feedback with content too short', function () {
+    $response = $this->postJson('/api/feedback', ['content' => 'short']);
+
+    $response->assertStatus(422)
+        ->assertJsonValidationErrors('content');
+});
+
+it('rejects feedback with content too long', function () {
+    $response = $this->postJson('/api/feedback', ['content' => str_repeat('a', 2001)]);
+
+    $response->assertStatus(422)
+        ->assertJsonValidationErrors('content');
+});
+
+it('rejects feedback with non-string content', function () {
+    $response = $this->postJson('/api/feedback', ['content' => ['array', 'value']]);
+
+    $response->assertStatus(422)
+        ->assertJsonValidationErrors('content');
+});
+
+it('accepts valid feedback and forwards to discord with mentions disabled', function () {
+    config()->set('constants.webhooks.feedback_discord_webhook', 'https://discord.com/api/webhooks/test');
+
+    $response = $this->postJson('/api/feedback', [
+        'content' => 'This is a valid feedback message for testing purposes.',
+    ]);
+
+    $response->assertStatus(200)
+        ->assertJson(['message' => 'Feedback sent.']);
+
+    Http::assertSent(function ($request) {
+        return $request->url() === 'https://discord.com/api/webhooks/test'
+            && $request['content'] === 'This is a valid feedback message for testing purposes.'
+            && $request['allowed_mentions'] === ['parse' => []];
+    });
+});
+
+it('does not forward to discord when webhook url is not configured', function () {
+    config()->set('constants.webhooks.feedback_discord_webhook', null);
+
+    $response = $this->postJson('/api/feedback', [
+        'content' => 'This is a valid feedback message for testing purposes.',
+    ]);
+
+    $response->assertStatus(200);
+
+    Http::assertNothingSent();
+});
+
+it('throttles feedback endpoint after 3 requests per minute', function () {
+    config()->set('constants.webhooks.feedback_discord_webhook', null);
+
+    for ($i = 0; $i < 3; $i++) {
+        $response = $this->postJson('/api/feedback', [
+            'content' => "Valid feedback message number {$i} for testing.",
+        ]);
+        $response->assertStatus(200);
+    }
+
+    $response = $this->postJson('/api/feedback', [
+        'content' => 'This fourth request should be throttled.',
+    ]);
+    $response->assertStatus(429);
+});
+
+it('disables discord mention parsing regardless of content', function () {
+    config()->set('constants.webhooks.feedback_discord_webhook', 'https://discord.com/api/webhooks/test');
+
+    $response = $this->postJson('/api/feedback', [
+        'content' => 'User feedback includes an @everyone style phrase and a link https://example.com for reference.',
+    ]);
+
+    $response->assertStatus(200);
+
+    Http::assertSent(function ($request) {
+        return $request['allowed_mentions'] === ['parse' => []];
+    });
+});