feat: add keyboard shortcuts help popup (Ctrl+Shift+/)

src/illogical/ui/main_window.py

@@ -17,6 +17,7 @@ from illogical.ui.loading_overlay import LoadingOverlay
 from illogical.ui.menu_bar import MenuBar
 from illogical.ui.plugin_table import PluginTableView
 from illogical.ui.restore_backup_window import RestoreBackupWindow
+from illogical.ui.shortcuts_help_window import ShortcutsHelpWindow
 from illogical.ui.sidebar import Sidebar
 
 if TYPE_CHECKING:
@@ -56,6 +57,7 @@ class MainWindow(QMainWindow):
         self._menu_bar.backup_now_triggered.connect(self._on_backup_now)
         self._menu_bar.restore_backup_triggered.connect(self._on_restore_backup)
         self._menu_bar.backup_settings_triggered.connect(self._on_backup_settings)
+        self._menu_bar.shortcuts_help_triggered.connect(self._show_shortcuts_help)
 
     def _setup_ui(self) -> None:
         self._central = QWidget()
@@ -113,6 +115,7 @@ class MainWindow(QMainWindow):
 
         self._restore_window: RestoreBackupWindow | None = None
         self._settings_window: BackupSettingsWindow | None = None
+        self._shortcuts_window: ShortcutsHelpWindow | None = None
 
     def showEvent(self, event: QShowEvent) -> None:  # noqa: N802
         super().showEvent(event)
@@ -470,6 +473,16 @@ class MainWindow(QMainWindow):
         self._sidebar.clear_manufacturer_search()
         self._sidebar.select_show_all()
 
+    def _show_shortcuts_help(self) -> None:
+        if self._shortcuts_window is not None:
+            self._shortcuts_window.close()
+        self._shortcuts_window = ShortcutsHelpWindow()
+        self._shortcuts_window.destroyed.connect(self._on_shortcuts_window_destroyed)
+        self._shortcuts_window.show_centered(self)
+
+    def _on_shortcuts_window_destroyed(self) -> None:
+        self._shortcuts_window = None
+
     def closeEvent(self, event: QCloseEvent) -> None:  # noqa: N802
         self._service.shutdown()
         self._backup_service.shutdown()

src/illogical/ui/menu_bar.py

@@ -14,6 +14,7 @@ class MenuBar(QMenuBar):
     backup_now_triggered = Signal()
     restore_backup_triggered = Signal()
     backup_settings_triggered = Signal()
+    shortcuts_help_triggered = Signal()
 
     def __init__(self, main_window: QMainWindow | None = None) -> None:
         super().__init__()
@@ -90,4 +91,9 @@ class MenuBar(QMenuBar):
         backup_menu.addAction(settings_action)
 
     def _setup_help_menu(self) -> None:
-        self.addMenu("Help")
+        help_menu = self.addMenu("Help")
+
+        shortcuts_action = QAction("Keyboard Shortcuts", self)
+        shortcuts_action.setShortcut(QKeySequence("Ctrl+Shift+/"))
+        shortcuts_action.triggered.connect(self.shortcuts_help_triggered)
+        help_menu.addAction(shortcuts_action)

src/illogical/ui/shortcuts_help_window.py

@@ -0,0 +1,169 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import pyqt_liquidglass as glass
+from PySide6.QtCore import Qt, QTimer
+from PySide6.QtWidgets import QGridLayout, QHBoxLayout, QLabel, QVBoxLayout, QWidget
+
+if TYPE_CHECKING:
+    from PySide6.QtGui import QKeyEvent
+
+SHORTCUTS: dict[str, list[tuple[str, str]]] = {
+    "Navigation": [
+        ("J / ↓", "Move down"),
+        ("K / ↑", "Move up"),
+        ("H / ←", "Collapse (categories)"),
+        ("L / →", "Expand (categories)"),
+        ("↩", "Enter category"),
+    ],
+    "Visual Mode": [("⇧V", "Select lines"), ("Esc", "Exit mode")],
+    "Quick Access": [
+        ("⌘1", "Show All"),
+        ("⌘2", "Uncategorized"),
+        ("⌘3", "Focus categories"),
+        ("⌘4", "Focus manufacturers"),
+        ("⌘F", "Search"),
+    ],
+    "Actions": [
+        ("⌥↩", "Context menu"),
+        ("⌥⇧↑", "Move category up"),
+        ("⌥⇧↓", "Move category down"),
+        ("⌘A", "Select all"),
+    ],
+    "Drag & Drop": [("⇧+Drop", "Add (don't move)")],
+    "Backup": [("⌘B", "Create backup"), ("⌘⇧R", "Restore")],
+}
+
+
+class ShortcutsHelpWindow(QWidget):
+    def __init__(self, parent: QWidget | None = None) -> None:
+        super().__init__(parent)
+        self._setup_window()
+        self._setup_ui()
+
+    def _setup_window(self) -> None:
+        self.setWindowTitle("Keyboard Shortcuts")
+        self.setWindowFlags(Qt.WindowType.Tool | Qt.WindowType.WindowStaysOnTopHint)
+        self.setAttribute(Qt.WidgetAttribute.WA_DeleteOnClose)
+
+    def _setup_ui(self) -> None:
+        layout = QVBoxLayout(self)
+        layout.setContentsMargins(40, 36, 40, 32)
+        layout.setSpacing(24)
+
+        title = QLabel("Keyboard Shortcuts")
+        title.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        title.setStyleSheet("""
+            font-size: 17px;
+            font-weight: 600;
+            color: white;
+            background: transparent;
+        """)
+        layout.addWidget(title)
+
+        grid = QGridLayout()
+        grid.setSpacing(32)
+        grid.setColumnStretch(0, 1)
+        grid.setColumnStretch(1, 1)
+
+        sections = list(SHORTCUTS.items())
+        for i, (section_name, shortcuts) in enumerate(sections):
+            col = i % 2
+            row = i // 2
+            section_widget = self._create_section(section_name, shortcuts)
+            grid.addWidget(section_widget, row, col, Qt.AlignmentFlag.AlignTop)
+
+        layout.addLayout(grid)
+        layout.addStretch()
+
+        hint = QLabel("Press Esc to close")
+        hint.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        hint.setStyleSheet("""
+            font-size: 11px;
+            color: rgba(255, 255, 255, 0.4);
+            background: transparent;
+        """)
+        layout.addWidget(hint)
+
+    def _create_section(self, title: str, shortcuts: list[tuple[str, str]]) -> QWidget:
+        section = QWidget()
+        section.setStyleSheet("background: transparent;")
+        layout = QVBoxLayout(section)
+        layout.setContentsMargins(0, 0, 0, 0)
+        layout.setSpacing(10)
+
+        header = QLabel(title)
+        header.setStyleSheet("""
+            font-size: 14px;
+            font-weight: 600;
+            color: rgba(255, 255, 255, 0.9);
+            background: transparent;
+            padding-bottom: 4px;
+        """)
+        layout.addWidget(header)
+
+        for key, description in shortcuts:
+            row = self._create_shortcut_row(key, description)
+            layout.addWidget(row)
+
+        return section
+
+    def _create_shortcut_row(self, key: str, description: str) -> QWidget:
+        row = QWidget()
+        row.setStyleSheet("background: transparent;")
+        layout = QHBoxLayout(row)
+        layout.setContentsMargins(0, 4, 0, 4)
+        layout.setSpacing(14)
+
+        key_label = QLabel(key)
+        key_label.setStyleSheet("""
+            font-size: 13px;
+            font-family: 'SF Mono', 'Menlo', monospace;
+            color: rgba(255, 255, 255, 0.95);
+            background: rgba(255, 255, 255, 0.1);
+            border-radius: 5px;
+            padding: 5px 10px;
+        """)
+
+        desc_label = QLabel(description)
+        desc_label.setStyleSheet("""
+            font-size: 13px;
+            color: rgba(255, 255, 255, 0.7);
+            background: transparent;
+        """)
+
+        layout.addWidget(key_label)
+        layout.addWidget(desc_label, 1)
+
+        return row
+
+    def keyPressEvent(self, event: QKeyEvent) -> None:  # noqa: N802
+        if event.key() == Qt.Key.Key_Escape:
+            self.close()
+            event.accept()
+            return
+        super().keyPressEvent(event)
+
+    def focusOutEvent(self, _event: object) -> None:  # noqa: N802
+        self.close()
+
+    def show_centered(self, parent: QWidget | None = None) -> None:
+        glass.prepare_window_for_glass(self, frameless=True)
+        self.adjustSize()
+        self.show()
+        self.activateWindow()
+        self.setFocus()
+
+        if parent:
+            parent_geo = parent.geometry()
+            x = parent_geo.center().x() - self.width() // 2
+            y = parent_geo.center().y() - self.height() // 2
+            self.move(x, y)
+
+        QTimer.singleShot(0, self._apply_glass)
+
+    def _apply_glass(self) -> None:
+        glass.apply_glass_to_window(
+            self, options=glass.GlassOptions(corner_radius=16.0)
+        )