Add Jan UI and selective Flatpak options

- Expose Jan as a core package and add a Hyprland shortcut (Mod + J). -
Refactor Flatpak module to provide per‑package enable options; default
package list is now empty. - Update librewolf search template to use a
single‑parameter URL. - Minor comment formatting changes across host
module files.

modules/home/hyprland/binds.nix

@@ -17,6 +17,7 @@ in {
       "$modifier, D, exec, vesktop"
       "$modifier, G, exec, affinity-v3"
       "$modifier, I, exec, iotas"
+      "$modifier, J, exec, Jan"
       "$modifier, L, exec, logseq"
       "$modifier, M, exec, plexamp"
       "$modifier, N, exec, dex ${desktopEntriesPath}/garandcloud.desktop"