Add Obsidian Leaflet plugin to BoM vault

Introduce a Nix derivation for the Obsidian Leaflet plugin and
configure the BoM vault to load it as a community plugin.

modules/home/obsidian/vaults/BoM.nix

@@ -1,4 +1,5 @@
 {
+  pkgs,
   lib,
   config,
   ...
@@ -8,5 +9,13 @@
   config.programs.obsidian.vaults."BoM" = lib.mkIf config.obsidian.vaults."BoM".enable {
     enable = true;
     target = "Obsidian/BoM";
+    settings.communityPlugins = [
+      {
+        enable = true;
+        pkg = pkgs.callPackage ../plugins/obsidian-leaflet.nix {};
+        # settings = {
+        # };
+      }
+    ];
   };
 }