Move Nix files into a nix directory

Move everything from `config` to the root level.

nix/lib/shared/scripts/t.nix

@@ -0,0 +1,38 @@
+{ pkgs }:
+
+{
+  name = "t";
+
+  runtimeInputs = with pkgs; [
+    openssl
+    tmux
+  ];
+
+  text = ''
+    # Based on similar scripts by ThePrimeagen and Jess Archer.
+
+    if [[ $# -eq 1 ]]; then
+      selected_path=$1
+    else
+      # Get the session name from fuzzy-finding list of directories and generating a
+      # tmux-safe version.
+      items=$(find "$REPOS" ~/Documents \
+        -maxdepth 1 -mindepth 1 -type d \
+        ! -name "_archive" \
+        ! -name "*-old" \
+        ! -name "*.old"
+      )
+
+      selected_path=$(echo "''${items}" | sort | fzf --reverse)
+    fi
+
+    session_name=$(basename "$selected_path" | sed 's/\./_/g')
+
+    if tmux switch-client -t="$session_name" 2>/dev/null; then
+      exit 0
+    fi
+
+    ( (tmux new-session -c "$selected_path" -d -s "$session_name" && tmux switch-client -t "$session_name") 2>/dev/null ) ||
+      tmux new-session -c "$selected_path" -A -s "$session_name"
+  '';
+}