add initial unsanitised dotfiles

Adds the clearest current starting point of my dotfiles I can make out.
There is no way to automate anything yet. Lots of stuff is missing from
the nix configuration, which needs to be added per machine.

picom.conf

@@ -0,0 +1,17 @@
+backend = "glx";
+
+corner-radius = 5.0;
+shadow = true;
+shadow-radius = 10;
+
+blur:
+{
+  method = "dual_kawase";
+}
+
+blur-background-exclude = [
+  "window_type = 'dock'",
+  "class_g ~= 'slop'",
+];
+
+vsync = true;