Make the shortcut list browsable and searchable

Replace the flat QTableWidget with a QTreeWidget that groups actions under
one collapsible top-level node per category. Fix the search box so it also
matches the current key sequence (exactly), accepts multi-keyword queries
(AND, any word order) and is accent-insensitive, auto-expands matching
groups and shows an "N actions" count. Add a quick filter (all / bound /
unbound / conflicts) that combines with the text query. Conflict detection,
per-row reset, reset-all and persistence are preserved.

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

sources/ui/configpage/shortcutsconfigpage.h

@@ -22,9 +22,12 @@
 
 #include <QKeySequence>
 
+class QComboBox;
 class QKeySequenceEdit;
+class QLabel;
 class QLineEdit;
-class QTableWidget;
+class QTreeWidget;
+class QTreeWidgetItem;
 
 /**
 	@brief The ShortcutsConfigPage class
@@ -47,21 +50,36 @@ class ShortcutsConfigPage : public ConfigPage
 
 	private slots:
 		void filterRows(const QString &filter_text);
+		void quickFilterChanged(int index);
 		void checkConflicts();
 		void resetAllRows();
 
 	private:
+		enum QuickFilter {
+			ShowAll = 0,
+			BoundOnly,
+			UnboundOnly,
+			ConflictsOnly
+		};
+
 		struct Row {
 			QString id;
+			QString category;
+			QString description;
 			QKeySequence default_sequence;
 			QKeySequenceEdit *edit;
+			QTreeWidgetItem *item;
+			bool conflicted;
 		};
 
 		void populateTable();
+		void applyFilter();
 		void resetRow(int row_index);
 
 		QLineEdit *m_filter_edit;
-		QTableWidget *m_table;
+		QComboBox *m_quick_filter;
+		QLabel *m_count_label;
+		QTreeWidget *m_tree;
 		QList<Row> m_rows;
 };