feat: add cross-browser extension with AI reading assistant

- Create Pi Reader browser extension for Chrome/Firefox
- Chrome uses Side Panel API, Firefox uses Sidebar Action API
- Supports both browsers with separate manifests and unified codebase
- Built with mini-lit components and Tailwind CSS v4
- Features model selection dialog with Ollama support
- Hot reload development server watches both browser builds
- Add useDefineForClassFields: false to fix LitElement reactivity

packages/browser-extension/src/utils/i18n.ts

@@ -0,0 +1,46 @@
+import { defaultEnglish, defaultGerman, type MiniLitRequiredMessages, setTranslations } from "@mariozechner/mini-lit";
+
+declare module "@mariozechner/mini-lit" {
+	interface i18nMessages extends MiniLitRequiredMessages {
+		Free: string;
+		"Input Required": string;
+		Cancel: string;
+		Confirm: string;
+		"Select Model": string;
+		"Search models...": string;
+		Format: string;
+		Thinking: string;
+		Vision: string;
+	}
+}
+
+const translations = {
+	en: {
+		...defaultEnglish,
+		Free: "Free",
+		"Input Required": "Input Required",
+		Cancel: "Cancel",
+		Confirm: "Confirm",
+		"Select Model": "Select Model",
+		"Search models...": "Search models...",
+		Format: "Format",
+		Thinking: "Thinking",
+		Vision: "Vision",
+	},
+	de: {
+		...defaultGerman,
+		Free: "Kostenlos",
+		"Input Required": "Eingabe erforderlich",
+		Cancel: "Abbrechen",
+		Confirm: "Bestätigen",
+		"Select Model": "Modell auswählen",
+		"Search models...": "Modelle suchen...",
+		Format: "Formatieren",
+		Thinking: "Thinking",
+		Vision: "Vision",
+	},
+};
+
+setTranslations(translations);
+
+export * from "@mariozechner/mini-lit/dist/i18n.js";