feat(market): portfolio modal — per-row delete, footer Close, instant Add, no bleed-through

- Delete moved from the footer to a per-row trash icon on each group (shown on
  hover/selected), with deferred deletion + selection fix-up.
- Removed the title-bar X; the footer is now right-aligned Revert / Save / Close
  (larger buttons), Close commits + dismisses. Esc and outside-click still close.
- Add entry now immediately creates a persisted "Untitled" group and selects it
  (no more invisible draft state); the -2 draft path is gone.
- Backdrop bleed-through fixed: when the modal is open the Market tab body is not
  rendered, so its content and foreground theme-effect borders no longer show over
  the overlay — the modal floats on the app's blurred/opaque backdrop.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/util/i18n.cpp

@@ -1166,6 +1166,8 @@ void I18n::loadBuiltinEnglish()
         strings_["portfolio_save"] = "Save";
         strings_["portfolio_cancel"] = "Cancel";
         strings_["portfolio_revert"] = "Revert";
+        strings_["portfolio_close"] = "Close";
+        strings_["portfolio_untitled"] = "Untitled";
         strings_["portfolio_detail_empty"] = "Select a group on the left, or add one, to edit it.";
         strings_["portfolio_add_to"] = "Add to portfolio";
         strings_["portfolio_remove_from"] = "Remove from portfolio";