feat: options dialog cleanup, menu/tree styling, light theme contrast

- Remove dead "Safe Mode" option, rename title case to "Uppercase menu items"
- Options tree: icons, themed hover/selection, mouse tracking (matches workspace tree)
- Tree item row padding (+4px) via MenuBarStyle CT_ItemViewItem for all trees
- Titlebar grows 2px when icon shown
- Menu popups: custom separator drawing, opaque background fill, flat hover highlight
- Menu bar/popup hover uses accent color (QPalette::Highlight) instead of grey
- Light theme: bump textMuted/textFaint contrast
- Dock grip widget for workspace and scanner docks

src/optionsdialog.h

@@ -15,7 +15,6 @@ struct OptionsResult {
     QString fontName;
     bool    menuBarTitleCase = true;
     bool    showIcon = false;
-    bool    safeMode = false;
     bool    autoStartMcp = true;
     int     refreshMs = 660;
     bool    generatorAsserts = false;
@@ -39,7 +38,6 @@ private:
     QComboBox*      m_fontCombo      = nullptr;
     QCheckBox*      m_titleCaseCheck = nullptr;
     QCheckBox*      m_showIconCheck  = nullptr;
-    QCheckBox*      m_safeModeCheck  = nullptr;
     QCheckBox*      m_autoMcpCheck   = nullptr;
     QSpinBox*       m_refreshSpin    = nullptr;
     QCheckBox*      m_assertCheck    = nullptr;