fix: prevent iframe from overriding file selection after file creation

When files change in the sidebar, setFilesInIframe sends the new files
to the iframe which responds with setActiveDocument defaulting to
App.tsx, overriding the user's selection. Now we ignore setActiveDocument
messages for 500ms after sending setFiles to the iframe.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/lib/components/raw_apps/RawAppEditor.svelte

@@ -164,10 +164,13 @@
 			setFilesInIframe(files)
 		}
 	}
+	let ignoreSetActiveDocument = false
 	function setFilesInIframe(newFiles: Record<string, string>) {
 		const files = Object.fromEntries(
 			Object.entries(newFiles).filter(([path, _]) => !path.endsWith('/'))
 		)
+		ignoreSetActiveDocument = true
+		setTimeout(() => (ignoreSetActiveDocument = false), 500)
 		iframe?.contentWindow?.postMessage(
 			{
 				type: 'setFiles',
@@ -612,6 +615,7 @@
 		} else if (e.data.type === 'updateModules') {
 			modules = e.data.modules
 		} else if (e.data.type === 'setActiveDocument') {
+			if (ignoreSetActiveDocument) return
 			// Normalize Windows-style path separators to Linux-style
 			selectedDocument = e.data.path?.replace(/\\/g, '/')
 		} else if (e.data.type === 'inspectorSelect') {