fix: README Mermaid flowchart — remove emoji and <br/>, use GitHub-compatible syntax

Author: TryWorld2026

README.md

@@ -170,12 +170,12 @@ Remember one entry: **`$tryworld-koubo`**. Hand it a script (Mode A) or ask for
 
 ```mermaid
 flowchart LR
-    U(["One sentence from you"]) --> P["🎬 tryworld-koubo<br/>Single entry, auto route"]
-    P -- "Mode A, script given" --> A["📜 tryworld-paper<br/>Optimize, confirm, produce"]
-    P -- "Mode B, pick a topic" --> S["🎯 tryworld-topics<br/>AIHOT news to topic list"]
+    U(("One sentence from you")) --> P["tryworld-koubo\nSingle entry · auto route"]
+    P -- "Mode A · script given" --> A["tryworld-paper\nOptimize · confirm · produce"]
+    P -- "Mode B · pick a topic" --> S["tryworld-topics\nAIHOT to topic list"]
     S -- "you choose" --> A
-    A --> O["✅ Deliverables<br/>Video, covers, titles, schedule"]
-    O -. automatic .-> M["📧 Email notice<br/>Deliverables and publish times"]
+    A --> O["Deliverables\nVideo · covers · titles · schedule"]
+    O -.->|"automatic"| M["Email notice\nDeliverables and publish times"]
 ```
 
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README.zh-CN.md

@@ -170,12 +170,12 @@ python -m pipeline.runner --project-dir <项目目录> --steps 3,4,5,6
 
 ```mermaid
 flowchart LR
-    U(["你的一句话"]) --> P["🎬 tryworld-koubo<br/>统一入口, 自动路由"]
-    P -- "模式 A, 直接给稿" --> A["📜 tryworld-paper<br/>优化, 确认, 出片"]
-    P -- "模式 B, 帮我选题" --> S["🎯 tryworld-topics<br/>AIHOT 资讯出选题清单"]
+    U(("你的一句话")) --> P["tryworld-koubo\n统一入口·自动路由"]
+    P -- "模式A·直接给稿" --> A["tryworld-paper\n优化·确认·出片"]
+    P -- "模式B·帮我选题" --> S["tryworld-topics\nAIHOT出选题清单"]
     S -- "你挑选" --> A
-    A --> O["✅ 成片交付<br/>视频, 封面, 标题, 发布计划"]
-    O -. 自动 .-> M["📧 邮件通知<br/>产物和四平台发布时间"]
+    A --> O["成片交付\n视频·封面·标题·发布计划"]
+    O -.->|"自动"| M["邮件通知\n产物和四平台发布时间"]
 ```
 
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