Initial commit: RR3 Community Server with web admin panel

- ASP.NET Core 8 REST API server
- 12 API endpoints matching EA Synergy protocol
- SQLite database with Entity Framework Core
- Web admin panel with Bootstrap 5
- User, Catalog, Session, Purchase management
- Comprehensive documentation

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

RR3CommunityServer/Pages/Users.cshtml.cs

@@ -0,0 +1,48 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.EntityFrameworkCore;
+using RR3CommunityServer.Data;
+using static RR3CommunityServer.Data.RR3DbContext;
+
+namespace RR3CommunityServer.Pages;
+
+public class UsersModel : PageModel
+{
+    private readonly RR3DbContext _context;
+
+    public UsersModel(RR3DbContext context)
+    {
+        _context = context;
+    }
+
+    public List<User> Users { get; set; } = new();
+    public string? SearchQuery { get; set; }
+
+    public async Task OnGetAsync(string? search)
+    {
+        SearchQuery = search;
+        
+        var query = _context.Users.AsQueryable();
+        
+        if (!string.IsNullOrEmpty(search))
+        {
+            query = query.Where(u => u.SynergyId.Contains(search) || u.DeviceId.Contains(search));
+        }
+        
+        Users = await query
+            .OrderByDescending(u => u.CreatedAt)
+            .ToListAsync();
+    }
+
+    public async Task<IActionResult> OnPostDeleteAsync(int userId)
+    {
+        var user = await _context.Users.FindAsync(userId);
+        if (user != null)
+        {
+            _context.Users.Remove(user);
+            await _context.SaveChangesAsync();
+        }
+        
+        return RedirectToPage();
+    }
+}