feat(market): rework Manage-Portfolio as a full-window master-detail modal

Combine the old list/edit modes into one master-detail view rendered as a
full-window overlay instead of a floating dialog.

- Backdrop: new material::DrawFullWindowBlurBackdrop draws an opaque base first
  (so the sheet is opaque regardless of the UI-opacity slider — the acrylic path
  multiplies its alpha by GetUIOpacity), then a strong full-window blur of the
  backdrop, gated exactly like DrawGlassPanel so low-performance mode skips the
  blur entirely (just the opaque scrim).
- Frame: bespoke full-window overlay (not BeginOverlayDialog) that mirrors the
  scrim plumbing and preserves both overlay popup gotchas verbatim (no focus-steal
  and no outside-click dismiss while a combo / color picker is open). Title-bar X,
  Esc, and outside-click all dismiss.
- Left (master): selectable group list with accent bar + icon + name + value line,
  and a pinned "Add group" button.
- Right (detail): live preview + label header, then a single-open accordion
  (Appearance = color + outline opacity + icon; Price; Addresses) so only one
  control group shows at a time — far less cluttered than the old two-column form.
- Footer: Delete / Revert / Save. Editing auto-commits named groups on navigation
  and on close (preserving grid geometry); unnamed drafts are dropped.
- s_pf_editing tri-state replaced by s_pf_sel (+ accordion open-state); the Manage
  button and grid-card click open with a valid selection.

Design + adversarial review done via multi-agent workflows (understand/design, then
a 3-lens ImGui-lifecycle / state-safety / backdrop review; zero confirmed defects).

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

src/util/i18n.cpp

@@ -1165,6 +1165,8 @@ void I18n::loadBuiltinEnglish()
         strings_["portfolio_delete"] = "Delete";
         strings_["portfolio_save"] = "Save";
         strings_["portfolio_cancel"] = "Cancel";
+        strings_["portfolio_revert"] = "Revert";
+        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";
         strings_["market_24h_change"] = "24h";