Native clipboard monitoring

[eltos]

This PR adds a native implementation to monitor for clipboard updates. Consequently, we no longer need SharpClipboard.

I hope this eliminates the spurious "Clipboard operation did not succeed" exceptions and thus closes #102, but to be sure, more testing is required.

[eltos]

@Juris-S can you help testing this change over the next weeks? Here is the preview binary:
https://github.com/eltos/PasteIntoFile/actions/runs/25606161741/artifacts/6897053370
Just extract this portable debug version anywhere, make sure to disable context menu entries and autostart for the other version you already had installed, and enabled them for this version.

If you could check that

• the native implementation works reliable and
• it resolves the spurious exceptions you reported

that would be much appreciated. If you encounter any issues, please report them here.