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.

public/mock/players.json

@@ -0,0 +1,37 @@
+[
+  {
+    "uuid": "8984c0b5-d912-4462-b189-c864fba4a1af",
+    "name": "DrKButz",
+    "discordId": "mock_discord_id",
+    "storyMarkdown": "# Mock Player Story\n\nThis is a mock player story that appears when the backend is unavailable.",
+    "tags": ["admin", "developer"],
+    "stats": {
+      "health": 100,
+      "armor": 50,
+      "money": 10000
+    },
+    "inventory": [
+      {"id": "weapon_pistol", "name": "Pistol", "quantity": 1},
+      {"id": "item_medkit", "name": "Medkit", "quantity": 3}
+    ],
+    "isOnline": false,
+    "lastSeen": "2025-01-01T12:00:00Z"
+  },
+  {
+    "uuid": "123e4567-e89b-12d3-a456-426614174000",
+    "name": "TestPlayer",
+    "discordId": null,
+    "storyMarkdown": "# Test Player\n\nThis is a test player for mock data purposes.",
+    "tags": ["player"],
+    "stats": {
+      "health": 80,
+      "armor": 30,
+      "money": 5000
+    },
+    "inventory": [
+      {"id": "item_food", "name": "Food", "quantity": 5}
+    ],
+    "isOnline": true,
+    "lastSeen": "2025-01-01T10:00:00Z"
+  }
+]