feat(webDev): add inquiry modal for pricing plans

This commit introduces a 'Contact Sales' modal on the web development page, allowing users to inquire about specific service plans.

- The pricing plan buttons now trigger this modal, pre-filled with the selected plan's details.
- Users can add custom remarks to their inquiry.
- On submission, a pre-formatted message is generated and opened in WhatsApp using a new `useWhatsAppMsgSender` composable.
- Adds `NUXT_PUBLIC_WHATSAPP_NUMBER` to the runtime configuration.
- Refactors content validation by introducing Zod schemas for `PricingPlan` and `Button` props to improve type safety.
- Adds new i18n keys for the modal interface and message templates.

app/composables/WhatsAppMsgSender.ts

@@ -0,0 +1,21 @@
+import { createSharedComposable } from "@vueuse/core";
+
+const _useWhatsAppMsgSender = () => {
+  const config = useRuntimeConfig();
+  const phone = config.public.whatsappNumber;
+
+  // --- WhatsApp 自动消息逻辑 ---
+  const sendMessage = (message: string) => {
+    const text = encodeURIComponent(message);
+    const url = `https://api.whatsapp.com/send?phone=${phone}&text=${text}`;
+    window.open(url, "_blank");
+  };
+
+  return {
+    sendMessage,
+  };
+};
+
+export const useWhatsAppMsgSender = createSharedComposable(
+  _useWhatsAppMsgSender
+);