add agenix support for secrets

shared/default.nix

@@ -1,5 +1,11 @@
-{
+let
+  sources = import ./sources/sources.nix;
+in {
   imports = [
+    # secrets
+    "${sources.agenix}/modules/age.nix"
+    ./../secrets
+
     ./base/common-config.nix
     ./platforms
     ./modules

shared/sources/sources.json

@@ -1,4 +1,16 @@
 {
+    "agenix": {
+        "branch": "main",
+        "description": "age-encrypted secrets for NixOS and Home manager",
+        "homepage": "https://matrix.to/#/#agenix:nixos.org",
+        "owner": "ryantm",
+        "repo": "agenix",
+        "rev": "3f1dae074a12feb7327b4bf43cbac0d124488bb7",
+        "sha256": "09aldzzc50121p0b3apj2c0l71jgmbif46a76shlgps8wbbbkr35",
+        "type": "tarball",
+        "url": "https://github.com/ryantm/agenix/archive/3f1dae074a12feb7327b4bf43cbac0d124488bb7.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
     "disko": {
         "branch": "master",
         "description": "Declarative disk partitioning and formatting using nix [maintainer=@Lassulus]",