feat: expand gen2D deck with deep technical slides and interactive elements

- Add 5 new slide pages: eino-deep-dive, ratelimit-overview, ratelimit-lua, async-deep-dive, harness
- Add 4 new drawio SVGs: pipeline-detail, ratelimit, async-task, harness
- Update all existing slides with v-clicks progressive reveal
- Add presenter notes and interactive prompts
- Expand slides.md to register all new pages (16 → 25+ slides)
- Fix text overflow by trimming content per Item block
- Add Eino Graph deep dive: WithGenLocalState, Pre/Post Handler, branch routing
- Add rate limiting section: algorithm comparison, Lua script, Gin middleware
- Add async task deep dive: TaskQueue FIFO, context progress injection
- Add consistency section: style/pipeline/data/deployment 4-layer guarantees

decks/gen2D/pages/async-deep-dive.md

@@ -0,0 +1,71 @@
+# 异步任务 — 队列与调度
+
+FIFO 串行执行，信号驱动调度
+
+<div class="mt-2">
+
+```go {1-6|8-12|all}
+type TaskQueue struct {
+    mu      sync.Mutex
+    jobs    []*TaskJob
+    ready   chan struct{}  // 新任务到达信号
+    stop    chan struct{}  // 优雅关闭信号
+}
+
+func (q *TaskQueue) Enqueue(job *TaskJob) {
+    q.mu.Lock()
+    q.jobs = append(q.jobs, job)
+    q.mu.Unlock()
+    q.ready <- struct{}{}  // 唤醒 run() 协程
+}
+```
+
+</div>
+
+<v-clicks>
+
+<Item title="Enqueue → run() → processNext() 流程">
+提交任务入队并发送信号。`run()` 协程阻塞等待信号，收到后调用 `processNext()` 取队首任务执行。FIFO 保证任务按提交顺序串行处理。
+</Item>
+
+<Item title="每个 Job 是一个闭包">
+`TaskJob` 封装了 `context.Context` 和执行函数。闭包捕获任务参数，context 控制超时和取消，确保每个任务独立且可中断。
+</Item>
+
+</v-clicks>
+
+---
+
+# 进度推送与 WebSocket
+
+Context 注入 + 多通道推送
+
+<div class="mt-2">
+
+```go {1-3|5-8|all}
+func WithProgressReporter(ctx context.Context, r ProgressReporter) context.Context {
+    return context.WithValue(ctx, progressCtxKey, r)
+}
+
+// 管线节点中使用
+reporter := GetProgressReporter(ctx)
+reporter.Report(Progress{Stage: "prompt", Percent: 25})
+```
+
+</div>
+
+<v-clicks>
+
+<Item title="进度阶段划分">
+5%（任务创建）→ 25%（提示词优化完成）→ 60%（素材生成完成）→ 80%（质检通过）→ 100%（格式适配 + 上传）。每个阶段由对应节点触发回调。
+</Item>
+
+<Item title="双通道推送">
+**WebSocket**：`ws://host/api/v1/tasks/:taskId/ws`，实时推送进度和结果。**HTTP 轮询**：`GET /api/v1/tasks/:taskId`，兼容降级方案。
+</Item>
+
+</v-clicks>
+
+<div class="flex justify-center mt-2">
+  <img src="../public/async-task.svg" class="w-full max-h-[180px] object-contain" />
+</div>