🏆 Add highscore feature with API endpoints, validations, and tests

- **Added:** Endpoints for submitting highscores (`highscores.store`) and retrieving the leaderboard (`highscores.index`).
- **Implemented:** Validation rules via `StoreHighscoreRequest` to ensure highscore integrity.
- **Included:** `Highscore` model, migration, and factory for data handling and seeding.
- **Enhanced:** Comprehensive feature tests covering submission, updating, retrieval, and payload validation.

app/Http/Requests/StoreHighscoreRequest.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace App\Http\Requests;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class StoreHighscoreRequest extends FormRequest
+{
+    /**
+     * Determine if the user is authorized to make this request.
+     */
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function expectsJson(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Get the validation rules that apply to the request.
+     *
+     * @return array<string, \Illuminate\Contracts\Validation\ValidationRule|array<mixed>|string>
+     */
+    public function rules(): array
+    {
+        return [
+            'npub' => ['required', 'string', 'starts_with:npub1', 'max:100'],
+            'name' => ['nullable', 'string', 'max:255'],
+            'satoshis' => ['required', 'integer', 'min:0'],
+            'blocks' => ['required', 'integer', 'min:0'],
+            'datetime' => ['required', 'date'],
+        ];
+    }
+
+    public function messages(): array
+    {
+        return [
+            'npub.required' => 'An npub is required to record the highscore.',
+            'npub.starts_with' => 'The npub must start with npub1.',
+            'name.string' => 'The name must be a valid string.',
+            'satoshis.required' => 'Please provide the earned satoshis amount.',
+            'satoshis.integer' => 'Satoshis must be a whole number.',
+            'blocks.required' => 'Please provide the number of blocks.',
+            'blocks.integer' => 'Blocks must be a whole number.',
+            'datetime.required' => 'Please provide when the score was achieved.',
+            'datetime.date' => 'The datetime value must be a valid date.',
+        ];
+    }
+}