feat(tui): Editor now handles extended character input (e.g., umlauts) and updates key binding documentation

packages/tui/README.md

@@ -115,7 +115,7 @@ editor.setAutocompleteProvider(provider);
 
 **Key Bindings:**
 - `Enter` - Submit
-- `Shift+Enter` or `Ctrl+Enter` - New line
+- `Shift+Enter`, `Ctrl+Enter`, or `Alt+Enter` - New line (terminal-dependent, Alt+Enter most reliable)
 - `Tab` - Autocomplete
 - `Ctrl+K` - Delete line
 - `Ctrl+A` / `Ctrl+E` - Line start/end

packages/tui/src/components/editor.ts

@@ -334,7 +334,7 @@ export class Editor implements Component {
 			this.moveCursor(0, -1);
 		}
 		// Regular characters (printable ASCII)
-		else if (data.charCodeAt(0) >= 32 && data.charCodeAt(0) <= 126) {
+		else {
 			this.insertCharacter(data);
 		}
 	}