add flake submodule flake reflection & fix secrix app

broken in 291bf42e2a
as `self` of flake was becoming inaccessible.
further hidden with a448ae9fb1
because it overloaded the former self argument

flake.nix

@@ -48,6 +48,7 @@
         # Usage in submodule:
         # { ... }@flakeArg: { }
         # add "..." this so new ones can easily be added
+        flake = self; # full flake reflection
         inherit
           # tools / shortcuts
           lib # nixpkgs & my lib combined

nix/apps/default.nix

@@ -1,7 +1,7 @@
 {
+  flake,
   inputs,
   lib,
-  self,
   ...
 }@flakeArg:
 { system, ... }@sysArg:
@@ -12,6 +12,6 @@
     assert lib.assertMsg (system == "x86_64-linux") ''
       secrix is currently only compatible with x86_64-linux
     '';
-    inputs.secrix.secrix self;
+    inputs.secrix.secrix flake;
 
 }