phase 2: move modules/ (server-*, desktop-*, shared); drop dotfiles no-rgb (superseded)

modules/server-power.nix

@@ -0,0 +1,41 @@
+{
+  ...
+}:
+{
+  powerManagement = {
+    enable = true;
+    cpuFreqGovernor = "powersave";
+  };
+
+  # Always-on server: disable all sleep targets.
+  systemd.targets = {
+    sleep.enable = false;
+    suspend.enable = false;
+    hibernate.enable = false;
+    hybrid-sleep.enable = false;
+  };
+
+  boot.kernelParams = [
+    # Disable NMI watchdog at boot. Eliminates periodic perf-counter interrupts
+    # across all cores (~1 W). Safe: apcupsd provides hardware hang detection
+    # via UPS, and softlockup watchdog remains active.
+    "nmi_watchdog=0"
+
+    # Route kernel work items to already-busy CPUs rather than waking idle ones.
+    # Reduces C-state exit frequency at the cost of slightly higher latency on
+    # work items -- irrelevant for a server whose latency-sensitive paths are
+    # all in userspace (caddy, jellyfin).
+    "workqueue.power_efficient=1"
+  ];
+
+  boot.kernel.sysctl = {
+    # Belt-and-suspenders: also set via boot param, but sysctl ensures it
+    # stays off if anything re-enables it at runtime.
+    "kernel.nmi_watchdog" = 0;
+  };
+
+  # Server has no audio consumers. Power-gate the HDA codec at module load.
+  boot.extraModprobeConfig = ''
+    options snd_hda_intel power_save=1 power_save_controller=Y
+  '';
+}