rename: temp_16tb -> Poup_16T throughout

- Module renamed to poup-16t-disk.nix
- Option namespace: gortium.poup16t (was gortium.temp16tb)
- LUKS name: poup_16t (was temp_16tb)
- Mount point: /mnt/Poup_16T (was /mnt/temp_16tb)
- btrbk instance: poup16t (was temp16tb)
- flake.nix import and host config updated

modules/nixos/filesystem/poup-16t-disk.nix

@@ -1,19 +1,19 @@
 { config, lib, pkgs, ... }:
 
 let
-  cfg = config.gortium.temp16tb;
+  cfg = config.gortium.poup16t;
   luksName = cfg.luksName;
 in
 with lib;
 
 {
-  options.gortium.temp16tb = {
-    enable = mkEnableOption "16TB temp storage disk (btrfs + LUKS + btrbk snapshots)";
+  options.gortium.poup16t = {
+    enable = mkEnableOption "Poup_16T storage disk (btrfs + LUKS + btrbk snapshots)";
 
     luksUuid = mkOption {
       type = types.str;
       description = ''
-        UUID of the LUKS partition on the 16TB disk.
+        UUID of the LUKS partition on the 16TB disk (WD Red Pro).
 
         Find this by running as root when the disk is connected:
           blkid /dev/sdb   # or wherever the disk appears
@@ -27,14 +27,14 @@ with lib;
 
     luksName = mkOption {
       type = types.str;
-      default = "temp_16tb";
+      default = "poup_16t";
       description = "Name for the LUKS /dev/mapper/ mapping";
     };
 
     mountPoint = mkOption {
       type = types.str;
-      default = "/mnt/temp_16tb";
-      description = "Mount point for the 16TB disk";
+      default = "/mnt/Poup_16T";
+      description = "Mount point for the 16TB data disk";
     };
 
     btrfsOptions = mkOption {
@@ -103,7 +103,7 @@ with lib;
 
     # btrbk — automated snapshot creation and rotation
     services.btrbk = mkIf cfg.btrbk.enable {
-      instances.temp16tb = {
+      instances.poup16t = {
         onCalendar = cfg.btrbk.schedule;
         settings = {
           snapshot_preserve_min = cfg.btrbk.preserveMin;