Add ollama dependency and dialog backdrop blur

- Add ollama package to web-ui dependencies for ModelSelector
- Add backdrop blur to SettingsDialog (bg-black/50 backdrop-blur-sm)
- Update mini-lit to 0.1.9 for backdropClassName prop support
- Fix TypeScript errors in ModelSelector (ollama import, parameter types)
- Add backward compatibility methods to SessionsStore (saveSession, loadSession, getLatestSessionId)

packages/web-ui/src/dialogs/SettingsDialog.ts

@@ -179,6 +179,7 @@ export class SettingsDialog extends LitElement {
 			},
 			width: "min(1000px, 90vw)",
 			height: "min(800px, 90vh)",
+			backdropClassName: "bg-black/50 backdrop-blur-sm",
 			children: html`
 				${DialogContent({
 					className: "h-full p-6",