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.

docs/index.md

@@ -1,14 +1,14 @@
----
-_layout: landing
----
-
-# EchoHub Documentation
-
-Welcome to the EchoHub documentation. EchoHub is a decentralized, IRC-like chat application built with .NET 10 and SignalR.
-
-## Quick Links
-
-- [Getting Started](articles/getting-started.md) - Set up and run EchoHub
-- [Architecture](articles/architecture.md) - Understand the system design
-- [API Reference](api/index.md) - Generated C# API documentation
-- [Changelog](changelog/index.md) - Release history
+---
+_layout: landing
+---
+
+# EchoHub Documentation
+
+Welcome to the EchoHub documentation. EchoHub is a decentralized, IRC-like chat application built with .NET 10 and SignalR.
+
+## Quick Links
+
+- [Getting Started](articles/getting-started.md) - Set up and run EchoHub
+- [Architecture](articles/architecture.md) - Understand the system design
+- [API Reference](api/index.md) - Generated C# API documentation
+- [Changelog](changelog/index.md) - Release history