VFS perf fixes, icon/stylesheet compat, download filename fix

VFS:
- Open backing fd at mo2_open time for read-only handles so mo2_read can
  splice without re-opening the file on every read call.
- Bump RLIMIT_NOFILE at mount time to fit the resulting fd pressure when
  the game keeps hundreds of BSAs open.
- Dedicated node_cache_mutex so resolveByInode / mo2_lookup stop racing
  unordered_map writes while multiple tree_mutex readers are active.
- max_read=1MB + matching conn->max_read and raised max_readahead/max_write
  so the kernel merges Wine's small sequential reads into bigger FUSE
  requests.
- Per-op wall-clock counters in mo2_init() logs so we can distinguish VFS
  latency from game-side work.

Proton launch:
- Write dxvk.conf to the prefix and set DXVK_CONFIG_FILE to force
  dxvk.enableGraphicsPipelineLibrary=False, avoiding long GPL compile
  stalls on first run.

UI / plugin compat:
- Clamp IconDelegate's per-icon width to [8, 16] so narrow content
  columns don't trigger QIcon::pixmap(0,0) returning null and logging
  "failed to load icon" every repaint.
- Pre-create lowercase symlinks in the stylesheet directory so QSS files
  authored on Windows resolve url(foo.svg) when on-disk files are Foo.svg.
- Flip content icons empty-chessboard.png and facegen.png to 8-bit RGBA
  so Qt's built-in PNG reader loads them uniformly.
- Add mobase.Version.canonicalString shim for legacy Python plugins that
  still call the old VersionInfo method on appVersion()'s return.
- BSPluginList: compare normalized plugin name lists instead of byte
  hashes so the post-run case-fix refresh stops spuriously firing the
  "load order changed" dialog.
- BSPluginList disabled by default.

Download manager:
- Parse CDN URL with QUrl + QUrlQuery and read the filename from the
  response-content-disposition query param (RFC 6266 quoted / unquoted /
  ext-value forms), not QFileInfo on the raw URL.
- When the API or URL gives us a CDN object key (no archive extension),
  prefer the actual Content-Disposition header from the live response in
  metaDataChanged and downloadFinished.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/libs/installer_bsplugins/src/GUI/ViewMarkingScrollBar.cpp b/libs/installer_bsplugins/src/GUI/ViewMarkingScrollBar.cpp
new file mode 100644
index 0000000..94da308
--- /dev/null
+++ b/libs/installer_bsplugins/src/GUI/ViewMarkingScrollBar.cpp
@@ -0,0 +1,80 @@
+#include "ViewMarkingScrollBar.h"
+
+#include <QPainter>
+#include <QStyle>
+#include <QStyleOptionSlider>
+
+namespace GUI
+{
+
+static QModelIndexList visibleIndexImpl(QTreeView* view, int column,
+                                        const QModelIndex& parent)
+{
+  if (parent.isValid() && !view->isExpanded(parent)) {
+    return {};
+  }
+
+  const auto* const model = view->model();
+  QModelIndexList index;
+  for (int i = 0; i < model->rowCount(parent); ++i) {
+    index.append(model->index(i, column, parent));
+    index.append(visibleIndexImpl(view, column, index.back()));
+  }
+  return index;
+}
+
+static QModelIndexList visibleIndex(QTreeView* view, int column)
+{
+  return visibleIndexImpl(view, column, QModelIndex());
+}
+
+ViewMarkingScrollBar::ViewMarkingScrollBar(QTreeView* view, int role)
+    : QScrollBar(view), m_View{view}, m_Role{role}
+{
+  // not implemented for horizontal sliders
+  Q_ASSERT(this->orientation() == Qt::Vertical);
+}
+
+QColor ViewMarkingScrollBar::color(const QModelIndex& index) const
+{
+  const auto data = index.data(m_Role);
+  if (data.canConvert<QColor>()) {
+    return data.value<QColor>();
+  }
+  return QColor();
+}
+
+void ViewMarkingScrollBar::paintEvent(QPaintEvent* event)
+{
+  if (m_View->model() == nullptr) {
+    return;
+  }
+  QScrollBar::paintEvent(event);
+
+  QStyleOptionSlider styleOption;
+  initStyleOption(&styleOption);
+
+  QPainter painter(this);
+
+  QRect handleRect = style()->subControlRect(QStyle::CC_ScrollBar, &styleOption,
+                                             QStyle::SC_ScrollBarSlider, this);
+  QRect innerRect  = style()->subControlRect(QStyle::CC_ScrollBar, &styleOption,
+                                             QStyle::SC_ScrollBarGroove, this);
+
+  auto indices = visibleIndex(m_View, 0);
+
+  painter.translate(innerRect.topLeft() + QPoint(0, 3));
+  const qreal scale =
+      static_cast<qreal>(innerRect.height() - 3) / static_cast<qreal>(indices.size());
+
+  for (int i = 0; i < indices.size(); ++i) {
+    const QColor color = this->color(indices[i]);
+    if (color.isValid()) {
+      painter.setPen(color);
+      painter.setBrush(color);
+      painter.drawRect(QRect(2, i * scale - 2, handleRect.width() - 5, 3));
+    }
+  }
+}
+
+}  // namespace GUI