feat: migrate from Next.js Pages Router to App Router with Payload CMS

Complete architectural overhaul migrating from Directus+tRPC to Payload CMS with Next.js App Router. This represents a fundamental shift in how the application is structured and how data is managed.

Major changes:
- Migrated from Pages Router (src/pages/) to App Router (src/app/)
- Replaced Directus CMS with Payload CMS as the content management system
- Removed tRPC in favor of Payload's built-in API routes
- Added PostgreSQL database via Docker Compose for local development
- Implemented separate route groups for frontend and Payload admin
- Updated all API routes to App Router conventions
- Added Payload collections for Projects, Technologies, Links, Media, and Users
- Configured ESLint for new project structure

Infrastructure:
- Added docker-compose.yml for PostgreSQL database
- Updated environment variables for Payload CMS configuration
- Integrated @payloadcms/next for seamless Next.js integration
- Added GraphQL API and playground routes

Dependencies:
- Upgraded React from 18.2.0 to 19.2.0
- Upgraded Next.js to 15.5.6
- Added Payload CMS 3.x packages (@payloadcms/db-postgres, @payloadcms/next, etc.)
- Removed Directus SDK and tRPC packages
- Updated Sharp to 0.34.x
- Migrated to @tanstack/react-query v5

src/app/(payload)/api/[...slug]/route.ts

@@ -0,0 +1,19 @@
+/* THIS FILE WAS GENERATED AUTOMATICALLY BY PAYLOAD. */
+/* DO NOT MODIFY IT BECAUSE IT COULD BE REWRITTEN AT ANY TIME. */
+import config from "../../../../payload.config";
+import "@payloadcms/next/css";
+import {
+  REST_DELETE,
+  REST_GET,
+  REST_OPTIONS,
+  REST_PATCH,
+  REST_POST,
+  REST_PUT,
+} from "@payloadcms/next/routes";
+
+export const GET = REST_GET(config);
+export const POST = REST_POST(config);
+export const DELETE = REST_DELETE(config);
+export const PATCH = REST_PATCH(config);
+export const PUT = REST_PUT(config);
+export const OPTIONS = REST_OPTIONS(config);