fix: improve project data handling and sitemap generation

Refactor project data parsing to ensure type safety by casting 
the project data as a string. Enhance the sitemap generation 
by fetching data from a dynamic API route, allowing for 
more accurate and up-to-date sitemap entries. Remove unused 
project markdown files to clean up the project structure. 
These changes improve code reliability and maintainability.

app/sitemap.tsx

@@ -1,31 +1,52 @@
-import {MetadataRoute} from "next";
-import fs from "fs";
-import path from "path";
+import type { MetadataRoute } from "next";
 
-export default function sitemap(): MetadataRoute.Sitemap {
-    const baseUrl = "https://dki.one";
+interface SitemapRoute {
+  url: string;
+  lastModified: string;
+  changeFrequency?:
+    | "always"
+    | "hourly"
+    | "daily"
+    | "weekly"
+    | "monthly"
+    | "yearly"
+    | "never";
+  priority?: number;
+}
 
-    // Static pages
-    const staticRoutes = [
-        {url: `${baseUrl}/`, lastModified: new Date().toISOString()},
-        {url: `${baseUrl}/privacy-policy`, lastModified: new Date().toISOString()},
-    ];
+export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
+  const baseUrl = "http://localhost:3000";
 
-    // Read project markdown files from the public folder
-    const projectsDirectory = path.join(process.cwd(), "public/projects");
-    let projectRoutes: { url: string; lastModified: string; }[] = [];
+  // Fetch the sitemap data from the dynamic API route
+  const response = await fetch(`${baseUrl}/api/sitemap`);
+  if (!response.ok) {
+    throw new Error(`Failed to fetch sitemap: ${response.statusText}`);
+  }
+  const sitemapData = (await response.json()) as SitemapRoute[];
 
-    if (fs.existsSync(projectsDirectory)) {
-        const projectFiles = fs.readdirSync(projectsDirectory).filter(file => file.endsWith(".md"));
+  return sitemapData.map((route) => {
+    let changeFrequency: SitemapRoute["changeFrequency"];
+    let priority: number;
 
-        projectRoutes = projectFiles.map((file) => {
-            const slug = file.replace(".md", "");
-            return {
-                url: `${baseUrl}/projects/${slug}`,
-                lastModified: new Date().toISOString(),
-            };
-        });
+    if (route.url === `${baseUrl}/`) {
+      changeFrequency = "weekly";
+      priority = 1.0;
+    } else if (route.url.startsWith(`${baseUrl}/projects`)) {
+      changeFrequency = "monthly";
+      priority = 0.8;
+    } else if (route.url.startsWith(`${baseUrl}/Blog`)) {
+      changeFrequency = "weekly";
+      priority = 0.6;
+    } else {
+      changeFrequency = "monthly";
+      priority = 0.5;
     }
 
-    return [...staticRoutes, ...projectRoutes];
+    return {
+      url: route.url,
+      lastModified: route.lastModified,
+      changeFrequency,
+      priority,
+    };
+  });
 }