Fix admin route access and backend configuration

- Added /admin redirect to login page in nginx config
- Fixed backend server.js route ordering for proper admin handling
- Updated authentication middleware and routes
- Added user management routes
- Configured PostgreSQL integration
- Updated environment configuration

Sky_Art_shop/Sky_Art_Shop.sln

@@ -0,0 +1,24 @@
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.2.0
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SkyArtShop", "SkyArtShop.csproj", "{18789CFC-15BE-BCAD-678C-3D46964FB388}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{18789CFC-15BE-BCAD-678C-3D46964FB388}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{18789CFC-15BE-BCAD-678C-3D46964FB388}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{18789CFC-15BE-BCAD-678C-3D46964FB388}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{18789CFC-15BE-BCAD-678C-3D46964FB388}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {245B1FFA-E45F-4311-AA3E-632F6507C697}
+	EndGlobalSection
+EndGlobal