- Add modular pinning system using NixOS module options
- Each desktop module now defines its own pinned applications:
* plasma.nix: konsole, dolphin, firefox, tigervnc
* gaming.nix: steam, discord
* office.nix: slack, signal, libreoffice-writer, libreoffice-calc
* dev.nix: windsurf
* media.nix: rustdesk
* dnm.nix: tor-browser, kleopatra (moved from crypto.nix)
- Move Plasma config from user-specific to desktop module for consistency
- Rename crypto.nix to dnm.nix and update references
- All users with Plasma desktop get automatic taskbar pinning
- Applications only appear when their desktop modules are active
