feat: Add comprehensive documentation suite and reorganize project structure

- Created complete documentation in docs/ directory
- Added PROJECT_OVERVIEW.md with feature highlights and getting started guide
- Added ARCHITECTURE.md with system design and technical details
- Added SECURITY.md with comprehensive security implementation guide
- Added DEVELOPMENT.md with development workflows and best practices
- Added DEPLOYMENT.md with production deployment instructions
- Added API.md with complete REST API documentation
- Added CONTRIBUTING.md with contribution guidelines
- Added CHANGELOG.md with version history and migration notes
- Reorganized all documentation files into docs/ directory for better organization
- Updated README.md with proper documentation links and quick navigation
- Enhanced project structure with professional documentation standards

Google/IO/Exception.php

@@ -0,0 +1,69 @@
+<?php
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+if (!class_exists('Google_Client')) {
+  require_once dirname(__FILE__) . '/../autoload.php';
+}
+
+class Google_IO_Exception extends Google_Exception implements Google_Task_Retryable
+{
+  /**
+   * @var array $retryMap Map of errors with retry counts.
+   */
+  private $retryMap = array();
+
+  /**
+   * Creates a new IO exception with an optional retry map.
+   *
+   * @param string $message
+   * @param int $code
+   * @param Exception|null $previous
+   * @param array|null $retryMap Map of errors with retry counts.
+   */
+  public function __construct(
+      $message,
+      $code = 0,
+      Exception $previous = null,
+      array $retryMap = null
+  ) {
+    if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
+      parent::__construct($message, $code, $previous);
+    } else {
+      parent::__construct($message, $code);
+    }
+
+    if (is_array($retryMap)) {
+      $this->retryMap = $retryMap;
+    }
+  }
+
+  /**
+   * Gets the number of times the associated task can be retried.
+   *
+   * NOTE: -1 is returned if the task can be retried indefinitely
+   *
+   * @return integer
+   */
+  public function allowedRetries()
+  {
+    if (isset($this->retryMap[$this->code])) {
+      return $this->retryMap[$this->code];
+    }
+
+    return 0;
+  }
+}