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.

content.config.ts

@@ -1,4 +1,5 @@
 import { defineContentConfig, defineCollection, z } from "@nuxt/content";
+import { PricingPlanPropsSchema } from "./app/schemas/PricingPlanSchema";
 
 const defineIndexSchema = () =>
   z.object({
@@ -50,36 +51,7 @@ const defineWebDevSchema = () =>
         icon: z.string().optional(), // 比如 "lucide:mouse-pointer-click"
         // 你原结构里通过 createService 包装，但最终是一个对象
         plans: z
-          .array(
-            z.object({
-              title: z.string().min(1),
-              description: z.string().optional(),
-              price: z.string().optional(), // 保持为 string（例如 "RM499 起"），如需更严可用 regex
-              discount: z.string().optional(),
-              tagline: z.string().optional(),
-              highlight: z.boolean().optional().default(false),
-              features: z.array(z.string()).optional().default([]),
-              button: z
-                .object({
-                  label: z.string().min(1),
-                  href: z.string().url().optional(), // 如果你可能会传链接
-                  // 预留扩展字段（例如：variant、target 等）
-                  variant: z
-                    .enum([
-                      "link",
-                      "solid",
-                      "outline",
-                      "soft",
-                      "subtle",
-                      "ghost",
-                    ])
-                    .default("subtle"),
-                  target: z.enum(["_self", "_blank"]).optional(),
-                })
-                .partial({ href: true, variant: true, target: true }) // 全部可选除 label（如果你希望 label 也可选，可把 min(1) 去掉或改 optional）
-                .optional(),
-            })
-          )
+          .array(PricingPlanPropsSchema)
           .min(1),
         // 预留扩展字段（例如：category、tags、hidden 等）
         category: z.string().optional(),