Strip :straight keywords from tangled config for container

straight.el is not available in the minimal container Emacs,
so we need to remove :straight nil and :straight t from
use-package declarations in the tangled config files.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

nixos/org-agenda-api.nix

@@ -19,10 +19,12 @@ let
       --eval '(require (quote org))' \
       --eval '(org-babel-tangle-file "work/org-config.org")'
 
-    # Copy all tangled files to output
+    # Copy all tangled files to output, stripping :straight keywords
+    # (straight.el is not available in the minimal container Emacs)
     for f in work/org-config-*.el; do
       if [ -f "$f" ]; then
-        cp "$f" $out/
+        # Remove :straight nil and :straight t from use-package declarations
+        sed -e 's/:straight nil//g' -e 's/:straight t//g' "$f" > "$out/$(basename "$f")"
       fi
     done