Abandon flakes in favour of npins

Flakes copy the whole gigantic repo to store all the time, quickly eating all the drive capacity.

site/mala-zahradka-pro-radost-cz.nix

@@ -0,0 +1,43 @@
+{
+  mkDerivation,
+  base,
+  containers,
+  directory,
+  extra,
+  filepath,
+  hakyll,
+  hakyll-contrib-tojnar,
+  pandoc,
+  process,
+  time,
+  lib,
+}:
+
+mkDerivation {
+  pname = "mala-zahradka-pro-radost-cz";
+  version = "0.0.1";
+
+  # Keep the contents of the src/ directory and top-level .cabal file.
+  src = lib.sourceByRegex ./. [
+    "^src(/.+|$)"
+    "[^/]+\.cabal$"
+  ];
+
+  isLibrary = false;
+  isExecutable = true;
+
+  executableHaskellDepends = [
+    base
+    containers
+    directory
+    extra
+    filepath
+    hakyll
+    hakyll-contrib-tojnar
+    pandoc
+    process
+    time
+  ];
+
+  license = lib.licenses.mit;
+}