feat(storefront): update FAQ and legal documentation

- Added new FAQ sections for account security, ordering and checkout, returns, shipping, and contact information.
- Introduced legal documents including privacy policy, terms of service, data protection, and general terms and conditions.
- Updated package dependencies to include gray-matter and remark-gfm for enhanced markdown support.

convex/messages.ts

@@ -0,0 +1,32 @@
+import { mutation } from "./_generated/server";
+import { v } from "convex/values";
+
+const topicValidator = v.union(
+  v.literal("products"),
+  v.literal("orders"),
+  v.literal("support"),
+  v.literal("other"),
+);
+
+/**
+ * Public mutation: submit a contact message. No auth required.
+ */
+export const submit = mutation({
+  args: {
+    fullName: v.string(),
+    email: v.string(),
+    topic: topicValidator,
+    message: v.string(),
+  },
+  handler: async (ctx, args) => {
+    const now = Date.now();
+    return await ctx.db.insert("messages", {
+      fullName: args.fullName,
+      email: args.email,
+      topic: args.topic,
+      message: args.message,
+      createdAt: now,
+      bookmarked: false,
+    });
+  },
+});