fix: remove missing includes/auth.php require from metrics and suggestions

Both endpoints tried to require a non-existent includes/auth.php and call
AuthMiddleware::requireAuth() — auth is already handled by api.php before
any endpoint file runs. This caused 500 errors on /api/metrics (which
blocked agent sparklines) and /api/suggestions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/endpoints/metrics.php

@@ -1,9 +1,7 @@
 <?php
 // Agent metrics history — returns CPU/RAM samples for sparklines
 require_once __DIR__ . '/../config.php';
-require_once __DIR__ . '/../../includes/auth.php';
 header('Content-Type: application/json');
-AuthMiddleware::requireAuth();
 
 $agentId = $_GET['agent_id'] ?? '';
 $hours   = min((int)($_GET['hours'] ?? 2), 24);

api/endpoints/suggestions.php

@@ -1,9 +1,7 @@
 <?php
 // Proactive suggestions endpoint — returns time-based command suggestions
 require_once __DIR__ . '/../config.php';
-require_once __DIR__ . '/../../includes/auth.php';
 header('Content-Type: application/json');
-AuthMiddleware::requireAuth();
 
 $hour = (int)date('G');
 $dow  = (int)date('w'); // 0=Sun, 6=Sat