feat(nix): add harmonia cache to nix.settings

Configure all NixOS machines to use the internal harmonia binary cache:
- Add nix-cache.johnogle.info as substituter
- Add harmonia signing public key to trusted-public-keys
- Enable fallback for local builds when cache unreachable
- Set 5s connect-timeout for faster fallback

Refs: x-qdkuu

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.lock

@@ -258,6 +258,22 @@
         "type": "github"
       }
     },
+    "nixpkgs-qt": {
+      "locked": {
+        "lastModified": 1770464364,
+        "narHash": "sha256-z5NJPSBwsLf/OfD8WTmh79tlSU8XgIbwmk6qB1/TFzY=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "23d72dabcb3b12469f57b37170fcbc1789bd7457",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-25.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "nixpkgs-unstable": {
       "locked": {
         "lastModified": 1769170682,
@@ -347,6 +363,7 @@
         "nix-darwin": "nix-darwin",
         "nix-doom-emacs-unstraightened": "nix-doom-emacs-unstraightened",
         "nixpkgs": "nixpkgs",
+        "nixpkgs-qt": "nixpkgs-qt",
         "nixpkgs-unstable": "nixpkgs-unstable",
         "perles": "perles",
         "plasma-manager": "plasma-manager",

flake.nix

@@ -4,6 +4,9 @@
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
     nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
+    # Separate nixpkgs for qt5webengine-dependent packages (jellyfin-media-player, etc.)
+    # Updates on separate Renovate schedule to avoid massive qt rebuilds
+    nixpkgs-qt.url = "github:nixos/nixpkgs/nixos-25.11";
 
     nix-darwin = {
       url = "github:nix-darwin/nix-darwin/nix-darwin-25.11";
@@ -76,6 +79,11 @@
         config.allowUnfree = true;
         overlays = unstableOverlays;
       };
+      # Separate nixpkgs for qt5webengine-heavy packages to avoid rebuild churn
+      qt-pinned = import inputs.nixpkgs-qt {
+        system = prev.stdenv.hostPlatform.system;
+        config.allowUnfree = true;
+      };
       custom = prev.callPackage ./packages {};
       # Compatibility: bitwarden renamed to bitwarden-desktop in unstable
       bitwarden-desktop = prev.bitwarden-desktop or prev.bitwarden;

home/home-kodi.nix

@@ -12,6 +12,7 @@
   home.roles = {
     base.enable = true;
     plasma-manager-kodi.enable = true;
+    kdeconnect.enable = true;
   };
 
   home.packages = with pkgs; [

renovate.json

@@ -13,7 +13,7 @@
   "lockFileMaintenance": {
     "enabled": true,
     "schedule": [
-      "before 5am on monday"
+      "after 2pm and before 4pm on Saturday"
     ]
   },
   "dependencyDashboard": true,
@@ -37,6 +37,9 @@
         "/^nixpkgs$/",
         "/^home-manager$/",
         "/^nix-darwin$/"
+      ],
+      "schedule": [
+        "after 2pm and before 4pm on Saturday"
       ]
     },
     {
@@ -48,6 +51,21 @@
       "matchPackageNames": [
         "/nixpkgs-unstable/",
         "/home-manager-unstable/"
+      ],
+      "schedule": [
+        "after 2pm and before 4pm on Saturday"
+      ]
+    },
+    {
+      "description": "nixpkgs-qt updates on Saturday (staggered from main ecosystem)",
+      "matchManagers": [
+        "nix"
+      ],
+      "matchPackageNames": [
+        "/nixpkgs-qt/"
+      ],
+      "schedule": [
+        "after 4pm and before 6pm on Saturday"
       ]
     },
     {

roles/common.nix

@@ -23,7 +23,13 @@
         max-jobs = "auto";
         trusted-users = [ "johno" ];
         substituters = [
+          "https://nix-cache.johnogle.info"
         ];
+        trusted-public-keys = [
+          "nix-cache.johnogle.info-1:IC5x8BxnrqkU9XqhMdDnZLtSg9Y3rBJVXhve5DJ92J0="
+        ];
+        fallback = true;
+        connect-timeout = 5;
       };
 
       gc = {