tb-scripts: add .sh extensions and add ,yt-dlp wrapper

Rename all shell script files to use .sh extensions for consistency
and better editor support (pushover-send, split-1G, xz, zipdir).
Update default.nix references to match the new filenames.

Add a new ,yt-dlp script that runs yt-dlp from nixpkgs-unstable
via `nix run`, so it's always up to date without needing to be
in the system packages.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkgs/tb-scripts/default.nix

@@ -20,25 +20,31 @@ pkgs.symlinkJoin {
     (pkgs.writeShellApplication {
       name = ",zipdir";
       runtimeInputs = [ pkgs.zip ];
-      text = builtins.readFile ./zipdir;
+      text = builtins.readFile ./zipdir.sh;
     })
 
     (pkgs.writeShellApplication {
       name = ",split-1G";
       runtimeInputs = [ pkgs.coreutils ];
-      text = builtins.readFile ./split-1G;
+      text = builtins.readFile ./split-1G.sh;
     })
 
     (pkgs.writeShellApplication {
       name = ",pushover-send";
       runtimeInputs = [ pkgs.curl ];
-      text = builtins.readFile ./pushover-send;
+      text = builtins.readFile ./pushover-send.sh;
     })
 
     (pkgs.writeShellApplication {
       name = ",xz";
       runtimeInputs = [ pkgs.xz ];
-      text = builtins.readFile ./xz;
+      text = builtins.readFile ./xz.sh;
+    })
+
+    (pkgs.writeShellApplication {
+      name = ",yt-dlp";
+      runtimeInputs = [ pkgs.nix ];
+      text = builtins.readFile ./yt-dlp.sh;
     })
   ];
 }

pkgs/tb-scripts/yt-dlp.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+exec nix run nixpkgs/nixpkgs-unstable#yt-dlp -- "$@"