Document how an app is launched, in both languages

F then 7 opens the F4HWN APPS menu and MENU runs the selection -- upstream's own wording in UVStudio's locales/en.js, and what App/apps/app_menu.c does: KEY_MENU on an installed row calls APP_LaunchOverlay, which runs until the app exits; EXIT leaves the menu. The page's hint now says it too.

Recorded with it: twenty keys short and long, the whole 79-entry settings menu and the multiboot menu all left the app region untouched (the multiboot menu reads firmware slots, not apps), and the way in turned out to be written in the flasher's translation file rather than the firmware source. When a feature's entry point is missing, the host tool that installs it is the document.

AGENTS.md

@@ -625,6 +625,22 @@ One thing that cost a round here: the server gives the emulator it starts a seri
 QEMU exit **before** it opens QMP -- which surfaces only as "QMP socket never appeared", with
 nothing else naming the cause. QEMU's option errors go to stdout, which the launcher discards.
 
+**Launching one is `F` then `7`, then MENU to run it.** That is upstream's own wording --
+UVStudio's `locales/en.js` says "launch them from the F + 7 menu" -- and it is what
+`App/apps/app_menu.c` does: `KEY_MENU` on an installed row calls `APP_LaunchOverlay(sel)`,
+which "runs until the app exits"; EXIT leaves the menu. Verified in the emulator, with
+`Tetris.app` installed through the page's own endpoint:
+
+    F, 7   -> the app region goes from 0 reads to 8, and a boxed "F4HWN APPS" screen appears
+    MENU   -> one read inside slot 0's code, and the game's own screen replaces the radio's
+    DOWN   -> the piece moves; the screen is still the game two seconds later
+
+For a while before that I could not find the way in at all: twenty keys short and long, the
+whole 79-entry settings menu, and the multiboot menu all left the app region untouched, and
+the multiboot menu reads firmware slots rather than apps. **The answer was written down in
+the flasher's own translation file**, not in the firmware source I had been reading -- so
+when a feature's entry point is missing, the host tool that installs it is the document.
+
 ## The keypad: two real bugs, both fixed
 
 The old note here said "keys reach the firmware but the UI does not react" and

AGENTS.zh-CN.md

@@ -507,6 +507,19 @@ UVStudio **只用槽 0..7 并显示为 1..8**；而且它**最后才写头** —
 缺 DLL 会让 QEMU **在打开 QMP 之前**就退出，而这只表现为"QMP socket never appeared"，
 没有别的线索。QEMU 的参数错误走的是 stdout，而启动器把它丢掉了。
 
+**启动方式是先按 `F` 再按 `7`，然后用 MENU 运行。** 这是上游自己的措辞 ——
+UVStudio 的 `locales/en.js` 原文是 "launch them from the F + 7 menu" —— 也正是
+`App/apps/app_menu.c` 的做法：在已安装的那一行按 `KEY_MENU` 会调用 `APP_LaunchOverlay(sel)`，
+它"一直运行到应用退出"；EXIT 退出菜单。在模拟器里验证过，`Tetris.app` 是通过页面自己的接口装的：
+
+    F, 7   -> app 区读取从 0 次变成 8 次，出现带框的 "F4HWN APPS" 界面
+    MENU   -> 槽 0 代码区出现 1 次读取，游戏自己的画面取代了电台界面
+    DOWN   -> 方块移动；两秒后屏幕上仍然是游戏
+
+在此之前我找了很久都进不去：二十个键的短按与长按、整整 79 项设置菜单、以及多系统菜单，都没让
+app 区被读过 —— 而多系统菜单读的是**固件槽**，不是应用。**答案写在刷机工具自己的翻译文件里**，
+不在我一直在读的固件源码里 —— 所以当一个功能的入口找不到时，**安装它的那个主机工具就是文档**。
+
 ## 键盘：两个真 bug，都已修复
 
 这里原来的笔记写的是"按键到达了固件但界面不反应"，并且归咎于机器模型。结果发现有**两个