feat: 知识批量沉淀改为后台任务,避免 nginx 504

- /ingest/threads/batch 新增 background 参数(默认 true),立即返回 {queued:true}
- 抽取循环抽出 _run_batch_ingest,后台路径显式传入 created_by
- 前端知识库页与输入框、线程 hooks/types 配套调整
- config.yaml 上下文压缩测试值

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend-web/src/components/workspace/input-box.tsx

@@ -10,6 +10,7 @@ import {
   LightbulbIcon,
   PaperclipIcon,
   PlusIcon,
+  ShrinkIcon,
   SparklesIcon,
   RocketIcon,
   XIcon,
@@ -329,6 +330,14 @@ export function InputBox({
     setLocalSettings("display", { ragModeEnabled: !ragModeEnabled });
   }, [ragModeEnabled, ragModeLocked, setLocalSettings]);
 
+  const contextCompressionEnabled =
+    localSettings.display.contextCompressionEnabled ?? false;
+  const handleContextCompressionToggle = useCallback(() => {
+    setLocalSettings("display", {
+      contextCompressionEnabled: !contextCompressionEnabled,
+    });
+  }, [contextCompressionEnabled, setLocalSettings]);
+
   const handleSubmit = useCallback(
     async (message: PromptInputMessage) => {
       if (status === "streaming") {
@@ -735,6 +744,35 @@ export function InputBox({
                 <span className="text-xs font-normal">参考文献</span>
               </PromptInputButton>
             </Tooltip>
+            <Tooltip
+              content={
+                contextCompressionEnabled
+                  ? "上下文压缩已开启：超长对话会自动压缩历史以节省 token"
+                  : "上下文压缩已关闭：点击开启"
+              }
+            >
+              <PromptInputButton
+                type="button"
+                aria-pressed={contextCompressionEnabled}
+                disabled={disabled}
+                className={cn(
+                  "gap-1.5! rounded-full px-3! shadow-none",
+                  compact && "rounded-lg px-2.5! py-1! text-[11px] font-medium",
+                  contextCompressionEnabled
+                    ? "border border-violet-300 bg-violet-50 text-violet-700 hover:bg-violet-100 dark:border-violet-700 dark:bg-violet-950/40 dark:text-violet-200"
+                    : compact
+                      ? "border border-transparent bg-muted/40 text-muted-foreground hover:bg-muted hover:text-foreground"
+                      : "border-0 bg-transparent text-muted-foreground hover:bg-muted/70 hover:text-foreground dark:text-slate-400 dark:hover:bg-slate-700/70 dark:hover:text-slate-100",
+                )}
+                onClick={handleContextCompressionToggle}
+              >
+                {contextCompressionEnabled && (
+                  <CheckIcon className="size-3 text-violet-700 dark:text-violet-200" />
+                )}
+                <ShrinkIcon className="size-3" />
+                <span className="text-xs font-normal">上下文压缩</span>
+              </PromptInputButton>
+            </Tooltip>
             <PromptInputActionMenu>
               <ModeHoverGuide
                 mode={