Guard optional Jenkins vars in database import and export

jenkins/Jenkinsfile.production-stdb-module-build

@@ -57,10 +57,12 @@ pipeline {
             git checkout --force "origin/$sourceBranch"
           }
           git clean -ffdx
-          git rev-parse HEAD | Set-Content -Encoding UTF8 .jenkins-source-commit
+          $resolvedCommit = (git rev-parse HEAD).Trim()
+          $utf8NoBom = New-Object System.Text.UTF8Encoding $false
+          [System.IO.File]::WriteAllText((Join-Path (Get-Location) '.jenkins-source-commit'), "$resolvedCommit`n", $utf8NoBom)
         '''
         script {
-          env.SOURCE_COMMIT = readFile('.jenkins-source-commit').trim()
+          env.SOURCE_COMMIT = readFile('.jenkins-source-commit').replace('\uFEFF', '').trim()
           env.EFFECTIVE_BUILD_VERSION = params.BUILD_VERSION?.trim() ? params.BUILD_VERSION.trim() : env.BUILD_NUMBER
         }
       }
@@ -92,18 +94,18 @@ pipeline {
                 throw '[stdb-build] 缺少 cargo。请先在 Windows 构建节点安装 Rust 工具链，并确保 cargo 在 PATH 中。'
               }
               # sccache 只是可选缓存；PATH 中存在但不可执行时必须回退到 rustc。
-          $sccacheCommand = Get-Command sccache -ErrorAction SilentlyContinue
+              $sccacheCommand = Get-Command sccache -ErrorAction SilentlyContinue
               $sccacheUsable = $false
-          if ($sccacheCommand) {
-            try {
-              & $sccacheCommand.Source --version | Out-Host
-              $sccacheUsable = $true
-            } catch {
-              Write-Host "[stdb-build] sccache 无法执行：$($_.Exception.Message)"
-            }
-          }
-          if (-not $sccacheUsable) {
-            Write-Host '[stdb-build] 未找到可用 sccache，改用 rustc 直接构建。'
+              if ($sccacheCommand) {
+                try {
+                  & $sccacheCommand.Source --version | Out-Host
+                  $sccacheUsable = $true
+                } catch {
+                  Write-Host "[stdb-build] sccache 无法执行：$($_.Exception.Message)"
+                }
+              }
+              if (-not $sccacheUsable) {
+                Write-Host '[stdb-build] 未找到可用 sccache，改用 rustc 直接构建。'
                 Remove-Item Env:RUSTC_WRAPPER -ErrorAction SilentlyContinue
               }
               npm run build:production-release -- --component spacetime-module --name "$env:EFFECTIVE_BUILD_VERSION"