treewide: yet another restructure

modules, overlays, and packages have their own default.nix re-exporting
things instead of reading file paths. slightly improves declarativeness.

wine-osu is removed; we're just using nix-gaming (for now).

our custom packages will now have to be accessed via pkgs.me instead of
just pkgs. helps know where it came from

future goals: get rid of our overlays completely, or at least not make
it replace anything from nixpkgs

hosts/blossom/kernel.nix

@@ -18,6 +18,6 @@
       "intel_pstate=passive"
       "msr.allow_writes=on"
     ];
-    kernelPackages = lib.mkForce (pkgs.linuxPackagesFor pkgs.linux-lava);
+    kernelPackages = lib.mkForce (pkgs.linuxPackagesFor pkgs.me.linux-lava);
   };
 }