feat: self-hosted GitLab Apps OAuth integration

Adds self-hosted GitLab OAuth sources so Coolify can connect to a self-managed GitLab instance, list private repositories, clone over an OAuth token, and deploy (the GitLab counterpart to GitHub Apps).

Hardening: authenticated, one-time team-bound OAuth callback state; token redaction in deploy logs; custom host port/path kept in clone and ls-remote URLs; submodule OAuth auth; system-wide source selection. Covered by unit and feature tests.

cosigned by OpenAI Codex at M1 Max

routes/webhooks.php

@@ -10,11 +10,13 @@ use Illuminate\Support\Facades\Route;
 Route::middleware(['web', 'auth', 'throttle:30,1'])->group(function () {
     Route::get('/source/github/redirect', [Github::class, 'redirect']);
     Route::get('/source/github/install', [Github::class, 'install']);
+    Route::get('/source/gitlab/redirect', [Gitlab::class, 'redirect']);
 });
 
 Route::post('/source/github/events', [Github::class, 'normal']);
 Route::post('/source/github/events/manual', [Github::class, 'manual']);
 
+Route::post('/source/gitlab/events', [Gitlab::class, 'normal']);
 Route::post('/source/gitlab/events/manual', [Gitlab::class, 'manual']);
 
 Route::post('/source/bitbucket/events/manual', [Bitbucket::class, 'manual']);