feat(app): add background RDP and RemoteApp keepalive

[SaltSpectre]

Feature and behavior changes:

• Removed all Hyper-V support from the tool, documentation, and installer, focusing solely on local, RDP, and RemoteApp sessions. [1] [2] [3]
• Replaced the previous method of activating (foregrounding) RDP and RemoteApp windows with a new approach that sends background mouse input, preventing session timeouts without disrupting the user's active window. [1] [2]
• Removed the RemoteApp whitelist feature; the tool now sends background input to all RemoteApp windows, as whitelisting is no longer necessary. [1] [2] [3]

Codebase and configuration updates:

• Added new helper functions (Get-ChildWindows, Send-BackgroundMouseMove, Send-BackgroundMouseJiggle, etc.) and updated the C# interop layer (user32.cs) to support background input and window enumeration. [1] [2] [3]
• Updated the default keystroke in documentation to {F15} (no modifiers), with fallback to Ctrl+Shift+F15 if invalid.

Other:

• Updated versioning and installer metadata to reflect the new direction and removed references to Hyper-V support. [1] [2] [3]