Scripts: subfolders of the Scripts and ScriptUI Panels folders become submenus

An extension that ships several panels no longer adds one Window menu entry per panel:
`Scripts/ScriptUI Panels/Motion Kit/Animate.jsx` shows as Window > Motion Kit > Animate.jsx,
and a subfolder of `Scripts/` is a submenu of File > Scripts. Top-level scripts are unchanged.

- Script names may be `Folder/File.jsx`: exactly one folder, each part a bare name (no `..`,
  `\`, NUL or empty part), never `ScriptUI Panels/...` under `Scripts/`.
- window.scriptPanel, file.runScript, file.uninstallScript, file.scripts.list and
  scriptui_panels.json take such names; a panel's tab is titled after its file.
- ConfigStore::list_dirs (DirConfig, MemoryConfig) lists the subfolders.
- menus::dynamic_nodes groups a folder's entries into a MenuNode::Submenu; the egui and native
  menus draw it with their submenu code.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/plugins.md

@@ -12,11 +12,11 @@ Guide):
 | After Effects | EffectCraft | |
 |---|---|---|
 | Effect plug-ins (C/C++ SDK, `.aex` / `.plugin`) | [Effect plug-ins](#effect-plug-ins): WebAssembly modules (plug-in API v1) or Rust; the `Plug-ins` folder next to the settings loads at start-up | Different ABI: After Effects SDK plug-ins can't run (G8) |
-| Scripts folder: its scripts are listed in File ▸ Scripts | `Scripts/` in the settings folder (File ▸ Scripts ▸ Install Script File… copies a script there), listed in File ▸ Scripts with the bundled samples | Same |
+| Scripts folder: its scripts are listed in File ▸ Scripts | `Scripts/` in the settings folder (File ▸ Scripts ▸ Install Script File… copies a script there), listed in File ▸ Scripts with the bundled samples; a subfolder (one level) is a submenu named after it | Same |
 | File ▸ Scripts ▸ Run Script File… (`.jsx`, `.jsxbin`) | `.jsx` / `.js` | Gap: `.jsxbin` (an undocumented binary encoding) |
 | ExtendScript preprocessor directives (`#include`, `#target`, `#targetengine`) | `#include` / `//@include` / `#includepath` inline files relative to the script (once each, depth-limited, file gate applies); `#target`, `#targetengine`, `#strict` are ignored | Same |
 | `Scripts/Startup` and `Scripts/Shutdown`: run in alphabetical order when the app starts and quits | Not run | Gap |
-| `Scripts/ScriptUI Panels`: listed at the bottom of the Window menu, dockable like the app's own panels, `this` is the panel | `Scripts/ScriptUI Panels/` in the settings folder (File ▸ Scripts ▸ Install ScriptUI Panel… copies one there), listed at the bottom of the Window menu, docked like any panel, `this` is the panel; the panels open when the app quits open again at the next launch | Same. Where a panel was docked isn't kept: workspace layouts aren't saved between launches |
+| `Scripts/ScriptUI Panels`: listed at the bottom of the Window menu, dockable like the app's own panels, `this` is the panel | `Scripts/ScriptUI Panels/` in the settings folder (File ▸ Scripts ▸ Install ScriptUI Panel… copies one there), listed at the bottom of the Window menu (a subfolder, one level, is a submenu named after it), docked like any panel, `this` is the panel; the panels open when the app quits open again at the next launch | Same. Where a panel was docked isn't kept: workspace layouts aren't saved between launches |
 | Keyboard shortcuts for scripts (the Keyboard Shortcuts editor lists the scripts of the Scripts folder) | Shortcuts bind to commands and menu entries; the File ▸ Scripts and Window menu entries of scripts aren't offered | Gap |
 | Running a script from the command line (`afterfx -r script.jsx`) | `effectcraft-cli script`, the control channel's and MCP's `script.run` | Same purpose, other entry points |
 | `app.settings` (kept in the preferences between sessions) | Kept in `script_settings.json` in the settings folder (`script.settings.get` / `script.settings.save`) | Same |
@@ -40,6 +40,9 @@ journaled and the same as the UI's action. The `effectcraft-script` crate's docs
   folder). It is listed in File ▸ Scripts at once (After Effects asks for a restart).
 * `file.scripts.list` lists installed and bundled scripts and panels; `file.runScript {name}` runs
   one; `file.uninstallScript {name}` removes an installed one.
+* A subfolder of `Scripts/` is a submenu of File ▸ Scripts named after the folder, and its scripts
+  are named `Folder/File.jsx` in these commands. One level of folders is listed; deeper folders
+  are not.
 
 ## ScriptUI panels
 
@@ -51,6 +54,13 @@ other panel. Closing the tab closes the panel (its `onClose` runs). Panels open
 quits open again at the next launch (`window.restoreScriptPanels`, which the desktop and web apps
 run at start-up; the list is `scriptui_panels.json` in the settings folder).
 
+To group panels, for example the several panels of one extension, make a subfolder of
+`Scripts/ScriptUI Panels/` and put them in it: `Scripts/ScriptUI Panels/My Tools/Animate.jsx` is
+listed as Window ▸ My Tools ▸ Animate.jsx, its tab is titled Animate, and commands name it
+`My Tools/Animate.jsx` (`window.scriptPanel {name}`). One level of folders is listed. Install
+ScriptUI Panel… copies a panel to the top of the folder; make the subfolder and move panels into it
+yourself.
+
 Run from File ▸ Scripts instead, the same script gets no panel, so it should make a floating
 palette itself. A minimal panel: