Fix race condition in named pipe server causing missed link clicks

[AaronFeledy]

Problem

When Hurl runs minimized to the system tray, clicking a link sometimes does nothing on the first click, but works on the second click. The tray service hasn't crashed—it just doesn't respond to the first invocation.

Root Cause

A race condition exists in the named pipe server communication between the Launcher and BrowserSelector:

1. The pipe server handles a connection and disposes the pipe
2. The loop restarts and creates a new pipe instance
3. Between dispose and recreation, no pipe exists
4. If the Launcher connects during this window, it falls back to spawning Hurl.exe
5. The spawned process signals the EventWaitHandle, which only shows the window—the URL is lost

Solution

Implement overlapping named pipe server instances that ensure at least one listener is always ready:

• Maintain 2-3 concurrent pipe listeners at all times
• When a connection is received, spawn a replacement listener before processing
• Use proper async/await instead of .Wait() anti-pattern
• Add 5-second read timeout to prevent hung connections
• Remove EventWaitHandle (no longer needed with robust pipe server)

Changes

• New: Source/Hurl.BrowserSelector/Services/NamedPipeUrlReceiver.cs - Encapsulated pipe server with overlapping listener pattern
• Modified: Source/Hurl.BrowserSelector/App.xaml.cs - Use new service, remove old pipe server and EventWaitHandle code

Fixes #202

[U-C-S]

Thanks for the PR. Will have a look later this week