refactor: remove UpgradeMode pass-through field from Core (#509)

* feat: simplify ClientTest/UpgradeTest for chain and cross-version integration testing

- Replace OSS/deprecated silent mode with a single mode-agnostic ClientTest entry point
- Remove CLI argument branching (chain/cross-version); the SDK's DownloadPlanBuilder
  selects CVP vs chain automatically based on server response (IsCrossVersion + FromVersion)
- Fix MSBuild CopyUpgradeTest target: stop excluding *.json so UpgradeTest.runtimeconfig.json
  is bundled as Update.exe, fixing 'hostpolicy.dll not found' launch error
- Improve events logging (IsCrossVersion/AppType/FromVersion display in OnUpdateInfo)
- Update UpgradeTest with clearer IPC flow documentation

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

* fix: address Copilot review feedback

- Replace hard-coded '%TEMP%/...' IPC path with Path.GetTempPath() at runtime
- Use OS-agnostic wording for strategy comments (WindowsStrategy → OS strategy)
- Use switch expression for AppType display to handle null/unknown values

* refactor: remove UpgradeMode field and related logic from Core

UpgradeMode was only a pass-through field in GeneralUpdate.Core with no
consuming logic. The server-side UpgradeService now always uses the
unified response flow (CVP first + chain fallback) instead of three-way
branching on UpgradeMode.

Changes:
- Remove UpgradeMode property from VersionEntry, DownloadAsset
- Remove UpgradeMode mapping in HttpDownloadSource and ClientStrategy

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: JusterZhu

src/c#/GeneralUpdate.Core/Configuration/VersionEntry.cs

@@ -164,24 +164,6 @@ public class VersionEntry : VersionIdentity
     [JsonPropertyName("urlExpireTimeUtc")]
     public DateTime? UrlExpireTimeUtc { get; set; }
 
-    /// <summary>
-    ///     The upgrade mode: 1 = VersionChain (sequential version upgrades), 2 = CrossVersion (cross-version upgrade).
-    /// </summary>
-    /// <remarks>
-    ///     <para>
-    ///         <list type="bullet">
-    ///             <item>
-    ///                 <description><c>1 (VersionChain)</c>: Upgrades through versions sequentially, without skipping intermediate versions.</description>
-    ///             </item>
-    ///             <item>
-    ///                 <description><c>2 (CrossVersion)</c>: Directly upgrades from an old version to any newer version.</description>
-    ///             </item>
-    ///         </list>
-    ///     </para>
-    /// </remarks>
-    [JsonPropertyName("upgradeMode")]
-    public int? UpgradeMode { get; set; }
-
     /// <summary>
     ///     Whether this is a cross-version upgrade package.
     ///     <c>true</c> indicates this package is used to upgrade directly from an old version to a new version,

src/c#/GeneralUpdate.Core/Download/Models/DownloadAsset.cs

@@ -18,7 +18,6 @@ public record DownloadAsset(
     bool IsForcibly = false,
     bool IsFreeze = false,
     int RecordId = 0,
-    int? UpgradeMode = null,
     int? AppType = null,
     string? AuthScheme = null,
     string? AuthToken = null

src/c#/GeneralUpdate.Core/Download/Sources/HttpDownloadSource.cs

@@ -178,7 +178,6 @@ private static DownloadAsset MapVersionEntry(VersionEntry v)
             IsForcibly: v.IsForcibly == true,
             IsFreeze: v.IsFreeze == true,
             RecordId: v.RecordId,
-            UpgradeMode: v.UpgradeMode,
             AppType: v.AppType,
             IsCrossVersion: v.IsCrossVersion == true,
             FromVersion: v.FromVersion,

src/c#/GeneralUpdate.Core/Strategy/ClientStrategy.cs

@@ -497,7 +497,6 @@ private async Task ExecuteStandardWorkflowAsync()
             IsForcibly = a.IsForcibly,
             IsFreeze = a.IsFreeze,
             AppType = a.AppType,
-            UpgradeMode = a.UpgradeMode,
             IsCrossVersion = a.IsCrossVersion,
             FromVersion = a.FromVersion
         }).ToList();