feat(core): Add support for building LLM applications (#7235)

This extracts all core and editor changes from #7246 and #7137, so that
we can get these changes merged first.

ADO-1120

[DB Tests](https://github.com/n8n-io/n8n/actions/runs/6379749011)
[E2E Tests](https://github.com/n8n-io/n8n/actions/runs/6379751480)
[Workflow Tests](https://github.com/n8n-io/n8n/actions/runs/6379752828)

---------

Co-authored-by: Jan Oberhauser <jan.oberhauser@gmail.com>
Co-authored-by: Oleg Ivaniv <me@olegivaniv.com>
Co-authored-by: Alex Grozav <alex@grozav.com>
Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

packages/editor-ui/src/components/HtmlEditor/HtmlEditor.vue

@@ -95,7 +95,9 @@ export default defineComponent({
 					{ key: 'Mod-Shift-z', run: redo },
 				]),
 				indentOnInput(),
-				theme,
+				theme({
+					isReadOnly: this.isReadOnly,
+				}),
 				lineNumbers(),
 				highlightActiveLineGutter(),
 				history(),
@@ -103,6 +105,7 @@ export default defineComponent({
 				dropCursor(),
 				indentOnInput(),
 				highlightActiveLine(),
+				EditorView.editable.of(!this.isReadOnly),
 				EditorState.readOnly.of(this.isReadOnly),
 				EditorView.updateListener.of((viewUpdate: ViewUpdate) => {
 					if (!viewUpdate.docChanged) return;