refactor: extract terminal launch logic into shared script

Add terminal-launcher script as a single entry point for launching
foot-based terminals with a given class and command. Migrate all
.desktop files to use it instead of inline foot invocations.

Simplify hyprland keybindings by replacing inline focus_or_launch
with hl.dsp.exec_cmd

desktop/nca-ai-01-herdr.desktop

@@ -2,7 +2,7 @@
 Version=1.0
 Name=nca-ai-01 herdr 
 Comment=remote dev
-Exec=foot -a nca-ai-01-herdr -T "nca ai 01 herdr" ssh nca-ai-01 mise exec -- herdr --session main
+Exec=terminal-launcher nca-ai-01-herdr "ssh nca-ai-01 mise exec -- herdr --session main"
 Terminal=false
 Type=Application
 Icon=foot