feat: Add DatabaseManager and LinkPlayer components, implement authentication and linking logic

- Created DatabaseManager component for managing database access via phpMyAdmin.
- Developed LinkPlayer component to link Discord accounts with game characters, including user authentication and error handling.
- Added mock data files for players, organizations, and projects to handle backend unavailability.
- Implemented AuthService for managing user authentication and session checks.
- Created DatabaseService to fetch and manage player, organization, and project data with fallback to mock data.
- Added HTML page for handling authentication unavailability.
- Developed a test script for validating Docker setup and required files.

backend/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "obsidian-backend",
+  "version": "1.0.0",
+  "description": "Backend for Obsidian RP Platform",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js"
+  },
+  "dependencies": {
+    "express": "^4.18.2",
+    "express-session": "^1.17.3",
+    "passport": "^0.6.0",
+    "passport-discord": "^0.1.4",
+    "cors": "^2.8.5",
+    "mysql2": "^3.6.0"
+  }
+}