P18 phase 2: stacked layout for the IDE (editor part)

CLAUDE.md

@@ -70,6 +70,7 @@ Worker messages:
 - **Layout and scrolling:** nested boxes show their variables below their code (CSS). The scroll effect follows the active box horizontally. It sets `scrollLeft`/`scrollTop` on the visualizer view only; don't use `scrollIntoView`, which also scrolls the LiaScript page around the embed and moves the step buttons.
 - **Console and Stop:** output, REPL inputs, Tests reports and notes form one transcript (`ConsoleEntry` list after `output`). While Python is busy for more than `STOP_BUTTON_DELAY`, the run button is **Stop**: `stopPython` terminates the worker and calls `startWorker` again, so the REPL namespace is gone after a stop. The embed reports this to its parent (protocol version 4, `glpython:busy`/`glpython:stop`).
 - **UI strings** come in via the `t: CoreStrings` prop. `src/i18n.ts` is their single source: `coreStrings` holds German and English, and `resolveUiLocale` picks the language. The embed uses them directly; the glpython IDE imports them and adds only its shell strings. New strings have been added as *optional* `CoreStrings` keys with an English fallback, so older hosts keep compiling; add both languages to `coreStrings`. Python values, reprs and error messages are never translated.
+- **Two layouts:** with `compact` (the embed) the original tree (`main-split` > `editor-column` + graphics aside), unchanged and styled by `src/embed/style.css`; without it (the IDE) the stacked layout (`workspace-stack`: `stack-top` with the editor panel and, while drawing, the graphics, then `stack-divider` and `stack-console`). Both are assembled from the same JSX pieces (`actionsNode`, `visualizerBarNode`, `editorWrapNode`, `consoleNode`, …) just before the return. The buttons can be portaled into the host's bar (`actionsContainer`).
 - **Embedded/reduced layouts:** the knobs are `compact`, `capabilities` (`WorkspaceCapabilities`, including `repl`) and `command` (`WorkspaceCommand`, an immutable `{id, type}` used by editor-free hosts to trigger run/visualize). Defaults must preserve the full-workspace behavior.
 
 **Embed protocol.** `src/embedProtocol.ts` defines the versioned message types and validators (`parseParentMessage`, `parseParentOrigin`, `GLPYTHON_EMBED_PROTOCOL_VERSION`, `GLPYTHON_MAX_SOURCE_LENGTH`), all re-exported from `src/index.ts`. The iframe (`src/embed/App.tsx`) requires an exact `parentOrigin` query param, sends `glpython:ready`/`glpython:resize`, and accepts `glpython:load`/`run`/`visualize`/`reset`. `run`/`visualize` carry the source snapshot so the parent remains the authoritative editor. Version 2 adds `files` + `mainFile` for programs of several files, version 3 adds `glpython:test` (doctests); version 4 adds `glpython:stop` and `glpython:busy`; the embed still accepts every earlier version and answers each parent in the version it last used, so older (e.g. cached) macros keep working. Modes: `eval` (with REPL), `turtle` (graphics layout), `visual` (visualizer-only, cannot exit). Reset remounts the workspace via a `key` generation counter, which also recreates the worker. Any protocol change should bump/handle the version and be covered in `scripts/check-embed-protocol.mjs`; also update `embed/demo.html` and the README.

README.md

@@ -211,6 +211,29 @@ it was. An input that doesn't compile has no button. Disable the REPL with
 `capabilities={{ repl: false }}`; the embed shows it in `eval` mode only, and
 resetting the embed discards the namespace.
 
+### Stacked layout (the IDE)
+
+Without `compact`, the workspace is stacked: the editor (or, while
+visualizing, the visualizer) in full width on top, a divider, and the console
+in full width below. The divider can be dragged (mouse, pen or finger) or
+moved with the arrow keys, Page Up/Down, Home and End (`consoleSize` names
+it); the console's share of the height (a third at first) is remembered in
+the browser. The file tabs and, while visualizing, the visualizer's bar take
+the same strip above the editor, so nothing below moves when switching. The
+graphics show beside the editor only while the program draws (for a
+visualization: if it draws at all); their ✕ hides them until the next drawing.
+An empty editor shows `editorPlaceholder` («Code hier eingeben»).
+
+The buttons come in the embed's order and labels - **▶ Run · Tests ·
+Visualize · Reset** (`runProject`, `runTests`, `visualize`, `resetOutput`) -
+and stay while visualizing (they leave the visualizer first). **Reset**
+restarts Python and clears the console, the visualization and the drawing, as
+the embed's Reset does. The run button keeps its width when it becomes
+**Stop**. A host can put the buttons into its own bar with
+`actionsContainer={element}` (the IDE's top bar); without it they sit above
+the editor. `capabilities={{ closeFileTabs: false }}` drops the ✕ on the file
+tabs, for a host that shows every file of the project as a tab.
+
 ### Compact embeds
 
 `GlPythonWorkspace` accepts optional `compact` and `capabilities` props. The