修正客户端完整性校验：补齐 CRC 后处理脚本并回绑 90CN.dll 指纹

问题：上一提交把 boundDll 指纹改成 1230336/F6DDA534…，但配套的
90CN.dll 未交付到客户端目录，服务端启动即被 verifyClientArtifacts 拦下
（client dll: size mismatch: 1230848 != 1230336），日志表现为空壳。

本次改动：
- 新增 client-patch/tools/patch_dll_crc.py，实现仓库中缺失的 DLL 自校验
  槽位回填（magic 0xC0DEC0DE + offset + 全文件 CRC32，跳过自身 4 字节），
  附带 verify 子命令可回读校验
- 新增 client-patch/tools/build_90cn.bat / .ps1，一键编译 + 打 CRC + 输出指纹
- client_build_id.go 指纹回绑到本次实际构建产物：
  1215488 / 30E41FF583893E611E6975DF96246E1320B042F7B33A32503C987F211D1776F5

验证：重编 DNF90Server.exe 后裸跑，完整性校验通过，PVF 加载完成，
dnfbridge 正常监听 :7001，game_ports=31，admin http 127.0.0.1:18111。

client-patch/tools/build_90cn.ps1

@@ -0,0 +1,96 @@
+# 90CN.dll one-click build script.
+#
+#   1. locate MSBuild (Build Tools / VS 2019 / VS 2022)
+#   2. build Release|Win32 from client-patch/90CN.vcxproj
+#   3. write the self-integrity CRC32 into the fresh DLL (patch_dll_crc.py)
+#   4. print the size + SHA-256 that client_build_id.go must carry
+#
+# Usage (from anywhere):
+#   powershell -ExecutionPolicy Bypass -File build_90cn.ps1
+#   powershell -ExecutionPolicy Bypass -File build_90cn.ps1 -SkipCrc
+#
+# The output DLL lands in client-patch\Release\90CN.dll and is copied to
+# ..\out\90CN.dll for convenience.
+
+param(
+    [switch]$SkipCrc,
+    [string]$Configuration = "Release",
+    [string]$Platform = "Win32"
+)
+
+$ErrorActionPreference = "Stop"
+$here = Split-Path -Parent $MyInvocation.MyCommand.Path
+$projectDir = Split-Path -Parent $here
+$vcxproj = Join-Path $projectDir "90CN.vcxproj"
+
+function Find-MSBuild {
+    $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+    if (Test-Path $vswhere) {
+        $path = & $vswhere -latest -products * -requires Microsoft.Component.MSBuild `
+            -find "MSBuild\**\Bin\MSBuild.exe" | Select-Object -First 1
+        if ($path) { return $path }
+    }
+    $candidates = @(
+        "C:\VS\BuildTools\MSBuild\Current\Bin\MSBuild.exe",
+        "${env:ProgramFiles}\Microsoft Visual Studio\2022\BuildTools\MSBuild\Current\Bin\MSBuild.exe",
+        "${env:ProgramFiles}\Microsoft Visual Studio\2022\Community\MSBuild\Current\Bin\MSBuild.exe",
+        "${env:ProgramFiles(x86)}\Microsoft Visual Studio\2019\BuildTools\MSBuild\Current\Bin\MSBuild.exe",
+        "${env:ProgramFiles(x86)}\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin\MSBuild.exe"
+    )
+    foreach ($c in $candidates) { if (Test-Path $c) { return $c } }
+    return $null
+}
+
+if (-not (Test-Path $vcxproj)) { throw "vcxproj not found: $vcxproj" }
+
+$msbuild = Find-MSBuild
+if (-not $msbuild) {
+    throw @"
+MSBuild not found.
+
+Install the free "Build Tools for Visual Studio" and tick:
+  - 使用 C++ 的桌面开发 (Desktop development with C++)
+  - MSVC v142 - VS 2019 C++ x64/x86 生成工具
+  - Windows 10 SDK
+
+Download: https://aka.ms/vs/17/release/vs_BuildTools.exe
+"@
+}
+
+Write-Host "[1/4] MSBuild : $msbuild"
+Write-Host "[2/4] building $Configuration|$Platform ..."
+
+& $msbuild $vcxproj /nologo /v:minimal /m `
+    /p:Configuration=$Configuration /p:Platform=$Platform
+if ($LASTEXITCODE -ne 0) { throw "build failed (exit $LASTEXITCODE)" }
+
+$dll = Join-Path $projectDir "$Configuration\90CN.dll"
+if (-not (Test-Path $dll)) { throw "build succeeded but $dll is missing" }
+
+if (-not $SkipCrc) {
+    Write-Host "[3/4] patching self-integrity CRC ..."
+    $python = (Get-Command python -ErrorAction SilentlyContinue).Source
+    if (-not $python) { $python = (Get-Command py -ErrorAction SilentlyContinue).Source }
+    if (-not $python) { throw "python not found; run with -SkipCrc or install Python" }
+    & $python (Join-Path $here "patch_dll_crc.py") patch $dll
+    if ($LASTEXITCODE -ne 0) { throw "CRC patch/verify failed" }
+} else {
+    Write-Host "[3/4] CRC patch skipped (-SkipCrc)"
+}
+
+$outDir = Join-Path (Split-Path -Parent $projectDir) "out"
+New-Item -ItemType Directory -Force -Path $outDir | Out-Null
+Copy-Item $dll (Join-Path $outDir "90CN.dll") -Force
+
+$size = (Get-Item $dll).Length
+$sha = (Get-FileHash $dll -Algorithm SHA256).Hash
+
+Write-Host "[4/4] done"
+Write-Host ""
+Write-Host "  dll   : $dll"
+Write-Host "  size  : $size"
+Write-Host "  sha256: $sha"
+Write-Host ""
+Write-Host "Update server/internal/services/dnfbridge/client_build_id.go with:"
+Write-Host "  boundDllBytes  = int64($size)"
+Write-Host "  boundDllSHA256 = `"$sha`""