Add GitHub Sync - Automated repository synchronization tool

Complete implementation of automated GitHub repository synchronization:
- Webhook-based auto-sync from GitHub
- Multi-repository support with branch selection
- Web dashboard for management
- Manual sync and rollback functionality
- Comprehensive logging and monitoring

Located in /gitpusher/ subdirectory as standalone application.

gitpusher/public/api/sync.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * Manual Sync API
+ * Triggers manual sync for a repository
+ */
+
+require_once '../../src/ConfigManager.php';
+require_once '../../src/Logger.php';
+require_once '../../src/GitHandler.php';
+
+header('Content-Type: application/json');
+
+if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
+    http_response_code(405);
+    echo json_encode(['error' => 'Method not allowed']);
+    exit;
+}
+
+$input = json_decode(file_get_contents('php://input'), true);
+
+if (empty($input['repo_id'])) {
+    http_response_code(400);
+    echo json_encode(['error' => 'Repository ID is required']);
+    exit;
+}
+
+$configManager = new ConfigManager();
+$logger = new Logger($configManager);
+$gitHandler = new GitHandler($logger, $configManager);
+
+$repo = $configManager->getRepository($input['repo_id']);
+
+if (!$repo) {
+    http_response_code(404);
+    echo json_encode(['error' => 'Repository not found']);
+    exit;
+}
+
+// Check if repository path exists
+if (!file_exists($repo['target_path'])) {
+    http_response_code(400);
+    echo json_encode(['error' => 'Repository path does not exist. Please clone first.']);
+    exit;
+}
+
+// Perform sync
+$logger->info($repo['id'], "Manual sync triggered");
+
+$result = $gitHandler->pull(
+    $repo['id'],
+    $repo['target_path'],
+    $repo['branch']
+);
+
+if ($result['success']) {
+    echo json_encode([
+        'success' => true,
+        'message' => $result['message'],
+        'files_changed' => $result['files_changed'] ?? 0,
+        'output' => $result['output']
+    ]);
+} else {
+    http_response_code(400);
+    echo json_encode([
+        'success' => false,
+        'message' => $result['message'],
+        'conflict' => $result['conflict'] ?? false,
+        'error' => $result['error'] ?? null,
+        'output' => $result['output'] ?? null
+    ]);
+}