fix: Improve Windows build scripts to properly execute electron-builder

- build-client.bat: Use node_modules\.bin\electron-builder.cmd directly
- build-all.ps1: Use direct path to electron-builder instead of npm run
- setup-backend.bat: Add UTF-8 support and use python -m pip

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/build-all.ps1

@@ -217,10 +217,20 @@ function Build-Electron {
             exit 1
         }
 
-        # 安裝依賴
-        if (-not (Test-Path "node_modules")) {
-            Write-Host "  安裝 npm 依賴..." -ForegroundColor Gray
-            npm install
+        # 總是執行 npm install 確保依賴完整
+        Write-Host "  安裝 npm 依賴..." -ForegroundColor Gray
+        npm install
+        if ($LASTEXITCODE -ne 0) {
+            Write-Err "npm install 失敗"
+            exit 1
+        }
+
+        # 確認 electron-builder 已安裝
+        $electronBuilderPath = Join-Path $ClientDir "node_modules\.bin\electron-builder.cmd"
+        if (-not (Test-Path $electronBuilderPath)) {
+            Write-Err "electron-builder 未安裝"
+            Write-Warn "請確認 package.json 中的 devDependencies 包含 electron-builder"
+            exit 1
         }
 
         # 建立 .env 如果不存在
@@ -230,12 +240,19 @@ function Build-Electron {
         }
 
         Write-Host "  執行 electron-builder..." -ForegroundColor Gray
-        npm run build -- --win
+
+        # 直接執行 node_modules 中的 electron-builder
+        & $electronBuilderPath --win
+
+        if ($LASTEXITCODE -ne 0) {
+            Write-Err "electron-builder 執行失敗"
+            exit 1
+        }
 
         if (Test-Path "dist\*.exe") {
             Write-OK "Electron 打包完成"
         } else {
-            Write-Err "Electron 打包失敗"
+            Write-Err "Electron 打包失敗 - dist 目錄中找不到 exe 檔案"
             exit 1
         }
     }