feat: implement modular foundation and core system services

- Update flake.nix with 25.11 release and core inputs
- Add dedicated modules for audio (Pipewire), bluetooth, and networking
- Update GEMINI.md with the new Modular Merging Architecture blueprint
- Configure graphical installer ISO and test VM outputs

modules/home/nightlight.nix

@@ -0,0 +1,14 @@
+{ config, pkgs, ... }:
+
+let
+  stateFile = "${config.home.homeDirectory}/.config/home-manager/hyprsunset-state.json";
+  hyprsunsetState = if builtins.pathExists stateFile then 
+    builtins.fromJSON (builtins.readFile stateFile)
+  else { enabled = false; temperature = 4000; };
+in
+{
+  services.hyprsunset = {
+    enable = true; # Always enabled, we control via IPC and state
+    temperature = if hyprsunsetState.enabled then hyprsunsetState.temperature else 6500;
+  };
+}