feat(notebook): add native Jupyter notebook editing and execution (#268)

Opens .ipynb files in a native notebook editor, in a project or LightEdit.

- crates/ide-notebook: lossless nbformat documents (unchanged notebooks save byte-for-byte, unknown fields kept, external changes detected) and owned local kernels over ZMQ via kernelspec — the selected Python environment only needs ipykernel, no Jupyter server.
- ide-host owns notebook documents per project incarnation and admits one execution batch at a time; outputs stream over IPC channels and kernel status is an IdeEvent.
- src/features/notebook: virtualized Python/Markdown cells, insert/delete/move/change type, Run Cell / Run All (Shift+Enter), interrupt, restart, interpreter selection from ide-sdk discovery, shared split views. Raw/unknown cells stay read-only.
- Custom editor kinds take part in dirty state, save/save all, undo/redo and Save/Don't Save/Cancel; closing editors from other features awaits that decision.
- Outputs: text, tracebacks, PNG/JPEG and sanitized SVG inline; HTML sanitized in a sandboxed iframe without allow-same-origin; JavaScript output is shown as inert source.
- Explicit launches (opening a notebook from the OS) win over session restoration.

Closes #131

Co-authored-by: dvictor357 <[email protected]>

src/features/remote-dev/index.ts

@@ -5,7 +5,8 @@
  */
 import { registerActions } from "@/platform/actions";
 import { disconnectRemote } from "@/platform/remote";
-import { registerOverlay } from "@/workbench/contributions";
+import { maybeEditorService, registerOverlay } from "@/workbench/contributions";
+import { confirmLeaveProject } from "@/platform/project";
 import { ConnectHost } from "./ConnectDialog";
 import { reloadEnvironment } from "./environment";
 import { closeConnectDialog, openConnectDialog } from "./model";
@@ -29,7 +30,15 @@ export function activate(): () => void {
         category: "File",
         keywords: ["ssh", "remote", "close"],
         when: "projectOpen",
-        run: () => disconnectRemote(),
+        run: async () => {
+          if (!(await confirmLeaveProject())) return;
+          try {
+            await disconnectRemote();
+          } catch (e) {
+            maybeEditorService()?.cancelClose?.();
+            throw e;
+          }
+        },
       },
       {
         id: "remote.reloadEnvironment",