feat(auth): streamline SOPS authentication and network configuration

- Replace age-based key decryption with automatic SSH host key support
- Simplify SSH configuration with consolidated host entries and enhanced security settings
- Upgrade home-manager to himmelblau for Microsoft Entra ID authentication
- Remove legacy agenix inputs and consolidate secrets to essential services only
- Add Cisco Secure Client overlay for enterprise VPN capabilities
- Update secrets.yaml to minimal configuration with gitea/github/hetzner services
- Expand system packages with tun module for VPN connectivity
- Add work directory setup for user development environment

flake.lock

@@ -1,52 +1,5 @@
 {
   "nodes": {
-    "agenix": {
-      "inputs": {
-        "darwin": "darwin",
-        "home-manager": "home-manager",
-        "nixpkgs": [
-          "nixpkgs"
-        ],
-        "systems": [
-          "systems"
-        ]
-      },
-      "locked": {
-        "lastModified": 1770165109,
-        "narHash": "sha256-9VnK6Oqai65puVJ4WYtCTvlJeXxMzAp/69HhQuTdl/I=",
-        "owner": "ryantm",
-        "repo": "agenix",
-        "rev": "b027ee29d959fda4b60b57566d64c98a202e0feb",
-        "type": "github"
-      },
-      "original": {
-        "owner": "ryantm",
-        "repo": "agenix",
-        "type": "github"
-      }
-    },
-    "darwin": {
-      "inputs": {
-        "nixpkgs": [
-          "agenix",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1744478979,
-        "narHash": "sha256-dyN+teG9G82G+m+PX/aSAagkC+vUv0SgUw3XkPhQodQ=",
-        "owner": "lnl7",
-        "repo": "nix-darwin",
-        "rev": "43975d782b418ebf4969e9ccba82466728c2851b",
-        "type": "github"
-      },
-      "original": {
-        "owner": "lnl7",
-        "ref": "master",
-        "repo": "nix-darwin",
-        "type": "github"
-      }
-    },
     "disko": {
       "inputs": {
         "nixpkgs": [
@@ -181,24 +134,24 @@
         "type": "github"
       }
     },
-    "home-manager": {
+    "himmelblau": {
       "inputs": {
         "nixpkgs": [
-          "agenix",
           "nixpkgs"
         ]
       },
       "locked": {
-        "lastModified": 1745494811,
-        "narHash": "sha256-YZCh2o9Ua1n9uCvrvi5pRxtuVNml8X2a03qIFfRKpFs=",
-        "owner": "nix-community",
-        "repo": "home-manager",
-        "rev": "abfad3d2958c9e6300a883bd443512c55dfeb1be",
+        "lastModified": 1783966245,
+        "narHash": "sha256-yFLScy0bxU6GLf4ZUoYCzZiyh5AGTT85evjw6xpG++g=",
+        "owner": "himmelblau-idm",
+        "repo": "himmelblau",
+        "rev": "00b27a924c2a42d54320b9ebc012c22d8dd95e28",
         "type": "github"
       },
       "original": {
-        "owner": "nix-community",
-        "repo": "home-manager",
+        "owner": "himmelblau-idm",
+        "ref": "main",
+        "repo": "himmelblau",
         "type": "github"
       }
     },
@@ -303,13 +256,13 @@
     },
     "root": {
       "inputs": {
-        "agenix": "agenix",
         "disko": "disko",
         "flake-compat": "flake-compat",
         "flake-parts": "flake-parts",
         "flake-utils": "flake-utils",
         "git-hooks-nix": "git-hooks-nix",
         "helium": "helium",
+        "himmelblau": "himmelblau",
         "import-tree": "import-tree",
         "nix-index-db": "nix-index-db",
         "nixos-24-05": "nixos-24-05",