Build: avoid deprecated Sass default import and add configurable pool timeout

- Prefer namespace import for  fallback to avoid default import deprecation
- Add BUILD_POOL_TIMEOUT to override thread-loader production pool timeout

Validated with prettier, eslint, and production build

Author: PeterDaveHello

build.mjs

@@ -53,8 +53,18 @@ if (Number.isInteger(rawWorkers) && rawWorkers > 0) {
   }
   threadWorkers = cpuCount
 }
-// Thread-loader pool timeout constants
-const PRODUCTION_POOL_TIMEOUT_MS = 2000
+// Thread-loader pool timeout constants (allow override via env)
+let PRODUCTION_POOL_TIMEOUT_MS = 2000
+if (process.env.BUILD_POOL_TIMEOUT) {
+  const n = parseInt(process.env.BUILD_POOL_TIMEOUT, 10)
+  if (Number.isFinite(n) && n > 0) {
+    PRODUCTION_POOL_TIMEOUT_MS = n
+  } else {
+    console.warn(
+      `[build] Invalid BUILD_POOL_TIMEOUT="${process.env.BUILD_POOL_TIMEOUT}", keep default ${PRODUCTION_POOL_TIMEOUT_MS}ms`,
+    )
+  }
+}
 // Enable threads by default; allow disabling via BUILD_THREAD=0
 const enableThread = process.env.BUILD_THREAD === '0' ? false : true
 
@@ -85,7 +95,9 @@ async function runWebpack(isWithoutKatex, isWithoutTiktoken, minimal, sourceBuil
     sassImpl = mod.default || mod
   } catch (e) {
     const mod = await import('sass')
-    sassImpl = mod.default || mod
+    // Prefer namespace import style to avoid deprecated default import warning
+    // "import sass from 'sass'" is deprecated; use namespace instead
+    sassImpl = mod
   }
 
   const dirKey = path.basename(sourceBuildDir || outdir)