Refactor and update various components of EchoHub.Server

- Updated launchSettings.json for consistency.
- Refactored FileValidationHelper to improve image validation logic.
- Enhanced ServerDirectoryService for better connection handling and user count updates.
- Improved DatabaseSetup for legacy database handling and seeding default channels.
- Refined FirstRunSetup to ensure JWT secret generation.
- Removed appsettings.Development.json as it is no longer needed.
- Updated EchoHub.Tests project file for consistency.
- Added unit tests for FileValidationHelper and PresenceTracker with improved assertions.
- Updated ValidationConstantsTests to ensure regex validations are correct.
- Cleaned up solution file formatting for better readability.

.config/dotnet-tools.json

@@ -1,12 +1,12 @@
-{
-  "version": 1,
-  "isRoot": true,
-  "tools": {
-    "docfx": {
-      "version": "2.78.3",
-      "commands": [
-        "docfx"
-      ]
-    }
-  }
-}
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "docfx": {
+      "version": "2.78.3",
+      "commands": [
+        "docfx"
+      ]
+    }
+  }
+}