docs: rewrite all XML documentation in English per MS guidelines

Comprehensive rewrite of all GeneralUpdate.Core XML documentation from
Chinese to English, following Microsoft official documentation conventions.
Every class, interface, struct, enum, field, property, method, constructor,
and delegate is now fully documented with:

- <summary> describing purpose and behavior
- <remarks> with step-by-step flow descriptions for core methods
- <param>, <returns>, <exception> tags for all public API
- <see cref> cross-references between related types
- <list type=table/bullet> where appropriate

Covering all 65 source files across 8 modules:
Bootstrap, Strategy, Pipeline, Download, Configuration, FileSystem,
Event/Differential, Network/Security/Silent.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: JusterZhu

src/c#/GeneralUpdate.Core/Bootstrap/GeneralUpdateBootstrap.cs

@@ -87,6 +87,13 @@ public GeneralUpdateBootstrap()
     }
 
     /// <summary>Cancel the current update operation.</summary>
+    /// <remarks>
+    /// Signals the internal <see cref="CancellationTokenSource"/> to request cancellation
+    /// of the ongoing update workflow. After calling this method, the running strategy
+    /// (e.g., <see cref="Strategy.ClientUpdateStrategy"/>) will observe the cancellation
+    /// token and terminate the current operation at the next safe checkpoint.
+    /// A cancellation message is also written to the trace log.
+    /// </remarks>
     public void Cancel()
     {
         _cts?.Cancel();
@@ -245,6 +252,15 @@ public GeneralUpdateBootstrap SetConfig(Configinfo configInfo)
     /// If just a filename (no directory separator), resolves relative to the current directory.
     /// Relative or absolute paths are used as-is.
     /// </param>
+    /// <returns>This bootstrap instance for chaining.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="filePath"/> is <c>null</c> or whitespace.</exception>
+    /// <exception cref="FileNotFoundException">Thrown when the specified file does not exist.</exception>
+    /// <exception cref="InvalidOperationException">Thrown when the JSON file cannot be deserialised into a valid <see cref="Configinfo"/>.</exception>
+    /// <remarks>
+    /// Reads the file content as UTF-8 JSON, deserialises it into a <see cref="Configinfo"/>
+    /// using the source-generated JSON serialisation context (<see cref="JsonContext.HttpParameterJsonContext"/>),
+    /// then delegates to <see cref="SetConfig(Configinfo)"/> for validation and mapping.
+    /// </remarks>
     public GeneralUpdateBootstrap SetConfig(string filePath)
     {
         if (string.IsNullOrWhiteSpace(filePath))
@@ -282,6 +298,21 @@ public GeneralUpdateBootstrap UseDiffPipeline(Action<DiffPipelineBuilder>? confi
         return this;
     }
 
+    /// <summary>
+    /// Registers a pre-check callback that is invoked after update information is retrieved
+    /// but before downloads begin. The callback can inspect the metadata and decide whether
+    /// to proceed with or abort the update.
+    /// </summary>
+    /// <param name="func">A predicate that receives <see cref="UpdateInfoEventArgs"/>
+    /// and returns <c>true</c> to continue or <c>false</c> to abort the update.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="func"/> is <c>null</c>.</exception>
+    /// <remarks>
+    /// The pre-check function is called during the client update strategy's standard workflow,
+    /// immediately after version comparison and before any packages are downloaded.
+    /// This allows conditional update logic, such as skipping updates under certain
+    /// network conditions or user preferences.
+    /// </remarks>
     public GeneralUpdateBootstrap AddListenerUpdatePrecheck(Func<UpdateInfoEventArgs, bool> func)
     {
         _updatePrecheck = func ?? throw new ArgumentNullException(nameof(func));
@@ -456,24 +487,64 @@ private GeneralUpdateBootstrap AddListener<TArgs>(Action<object, TArgs> action)
         return this;
     }
 
+    /// <summary>
+    /// Registers a callback for the multi-all-download-completed event, raised when all
+    /// update files across all versions have been downloaded.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerMultiAllDownloadCompleted(
         Action<object, MultiAllDownloadCompletedEventArgs> cb) => AddListener(cb);
 
+    /// <summary>
+    /// Registers a callback for the multi-download-completed event, raised when a single
+    /// version's set of files has finished downloading.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerMultiDownloadCompleted(
         Action<object, MultiDownloadCompletedEventArgs> cb) => AddListener(cb);
 
+    /// <summary>
+    /// Registers a callback for the multi-download-error event, raised when an error
+    /// occurs during batch download.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerMultiDownloadError(
         Action<object, MultiDownloadErrorEventArgs> cb) => AddListener(cb);
 
+    /// <summary>
+    /// Registers a callback for download statistics events, providing real-time throughput
+    /// and progress information during batch downloads.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerMultiDownloadStatistics(
         Action<object, MultiDownloadStatisticsEventArgs> cb) => AddListener(cb);
 
+    /// <summary>
+    /// Registers a callback for exception events raised during the update workflow.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerException(
         Action<object, ExceptionEventArgs> cb) => AddListener(cb);
 
+    /// <summary>
+    /// Registers a callback for update-information events, providing version metadata
+    /// retrieved from the server.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerUpdateInfo(
         Action<object, UpdateInfoEventArgs> cb) => AddListener(cb);
 
+    /// <summary>
+    /// Registers a callback for general progress events during the update process.
+    /// </summary>
+    /// <param name="cb">The callback to invoke.</param>
+    /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap AddListenerProgress(
         Action<object, ProgressEventArgs> cb) => AddListener(cb);