Refactor server structure and enhance middleware functionality

- Consolidated middleware setup into a dedicated setup file for better organization.
- Introduced API proxy middleware to handle requests to the backend API.
- Registered well-known, merge, and SSR routes in separate files for improved modularity.
- Removed unused HTML and SSR layout files to streamline the codebase.
- Implemented a utility for HTML escaping to prevent XSS vulnerabilities.
- Updated the main server entry point to utilize the new middleware and route structure.

src/server/middlewares/setup.ts

@@ -0,0 +1,20 @@
+import { contextStorage } from 'hono/context-storage';
+import { cors } from 'hono/cors';
+import isMobile from 'is-mobile';
+import type { Hono } from 'hono';
+
+export function setupMiddlewares(app: Hono) {
+  app.use('*', contextStorage());
+  
+  app.use(cors(), async (c, next) => {
+    c.set("fetch", app.request.bind(app));
+    
+    const ua = c.req.header("User-Agent");
+    if (!ua) {
+      return c.json({ error: "User-Agent header is missing" }, 400);
+    }
+    
+    c.set("isMobile", isMobile({ ua }));
+    await next();
+  });
+}