refactor(scripts): split monolithic module into per-script submodules

Extract shared `mkScript` and `mkScriptModule` helpers into `lib.nix`
Split each script into `modules/scripts/<name>/` with its own
  `default.nix`, `script.sh`, and `assertions.nix`
Remove `conditions` parameter from `mkScriptModule`; move condition
  assertions into per-script `assertions.nix` files with inline checks
  and error messages
Simplify `mkScriptModule` to return `{ options, moduleConfig }` instead
  of a module function, taking `config` as a direct parameter
Add `description` field to `mkScript` that inserts the description as
  a `# <text>` comment between the shebang and env vars
Thread `description` through `mkScriptModule` to each `default.nix`
Move top comment lines from each `script.sh` into the `description`
  field and remove from sources to avoid duplication
Remove old flat `.sh` files from `modules/scripts/` root

3 files changed, 76 insertions, 0 deletions

diff --git a/modules/scripts/system-monitor/assertions.nix b/modules/scripts/system-monitor/assertions.nix
new file mode 100644
index 0000000..0710fc3
--- /dev/null
+++ b/modules/scripts/system-monitor/assertions.nix
@@ -0,0 +1,19 @@
+{ config, ... }:
+[
+  {
+    assertion = !config.scripts.system-monitor.enable || config.system.bottom.enable;
+    message = "scripts.system-monitor is enabled but requires `system.bottom.enable`.";
+  }
+  {
+    assertion = !config.scripts.system-monitor.enable || config.system.nvtop.enable;
+    message = "scripts.system-monitor is enabled but requires `system.nvtop.enable`.";
+  }
+  {
+    assertion = !config.scripts.system-monitor.enable || config.terminal.tmux.enable;
+    message = "scripts.system-monitor is enabled but requires `terminal.tmux.enable`.";
+  }
+  {
+    assertion = !config.scripts.system-monitor.enable || config.terminal.kitty.enable;
+    message = "scripts.system-monitor is enabled but requires `terminal.kitty.enable`.";
+  }
+]
diff --git a/modules/scripts/system-monitor/default.nix b/modules/scripts/system-monitor/default.nix
new file mode 100644
index 0000000..1f4990b
--- /dev/null
+++ b/modules/scripts/system-monitor/default.nix
@@ -0,0 +1,32 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  inherit ((import ../lib.nix { inherit lib pkgs; })) mkScriptModule;
+  base = mkScriptModule {
+    name = "system-monitor";
+    path = ./script.sh;
+    description = "System monitor script using tmux to run bottom and nvtop side-by-side\nOpens a tmux session with:\n  - Left pane: bottom (system/process monitor)\n  - Right pane: nvtop (GPU monitor)";
+    deps = [
+      config.system.bottom.package
+      config.system.nvtop.package
+      config.terminal.tmux.package
+      config.terminal.kitty.package
+      pkgs.bash
+    ];
+    desktop = {
+      enable = true;
+      displayName = "System Monitor";
+    };
+    inherit config;
+  };
+in
+{
+  options = base.options;
+  config = base.moduleConfig // {
+    assertions = base.moduleConfig.assertions ++ (import ./assertions.nix { inherit config lib; });
+  };
+}
diff --git a/modules/scripts/system-monitor/script.sh b/modules/scripts/system-monitor/script.sh
new file mode 100644
index 0000000..951428c
--- /dev/null
+++ b/modules/scripts/system-monitor/script.sh
@@ -0,0 +1,25 @@
+SESSION="system-monitor"
+
+kitty @ set-font-size -- -4
+
+cleanup() {
+  kitty @ set-font-size -- +4
+}
+trap cleanup EXIT INT TERM
+
+# Kill any existing session
+tmux kill-session -t "$SESSION" 2>/dev/null
+
+# Start new tmux session with btm wrapped to kill session on exit
+tmux new-session -d -s "$SESSION" -c "$HOME" "bash -c 'btm; tmux kill-session -t $SESSION'"
+
+# Split horizontally: right pane runs nvtop wrapped similarly
+tmux split-window -h -t "$SESSION:0" -c "$HOME" "bash -c 'nvtop; tmux kill-session -t $SESSION'"
+
+tmux set -g status off
+tmux set -g mouse on
+tmux set -g focus-events on
+
+# Select main pane and attach
+tmux select-pane -t "$SESSION:0.0"
+tmux attach-session -t "$SESSION"