Rework keyboard shortcuts with app-level event filter

- Replace QShortcut with QApplication eventFilter to intercept
  Ctrl+C/S/N/W/D/F/R before widgets consume them
- New bindings: Ctrl+N (new tab), Ctrl+C (clear log), Ctrl+S (find),
  Ctrl+F (flash), Ctrl+D (connect/disconnect), Ctrl+R (normal mode)
- Single bindings tuple as source of truth for key map and help dialog
- Apply saved font settings via one-shot showEvent (after stylesheet)
- Add Shortcuts entry under Help menu
- Remove unused imports (QShortcut, QKeySequence, QMenuBar)

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

ameba_control_panel/app.py

@@ -4,20 +4,19 @@ import logging
 import logging.handlers
 import sys
 
-from PySide6.QtCore import Qt
+from PySide6.QtCore import QEvent, Qt
-from PySide6.QtGui import QFont, QKeySequence, QShortcut
+from PySide6.QtGui import QFont
 from PySide6.QtWidgets import (
     QApplication,
     QInputDialog,
     QMainWindow,
-    QMenuBar,
     QMessageBox,
     QTabWidget,
     QToolButton,
 )
 
 from ameba_control_panel import config
-from ameba_control_panel.config import DeviceProfile
+from ameba_control_panel.config import DeviceProfile, Mode
 from ameba_control_panel import theme
 from ameba_control_panel.controllers.device_tab_controller import DeviceTabController
 from ameba_control_panel.services.session_store import SessionStore
@@ -39,10 +38,11 @@ class MainWindow(QMainWindow):
         self._settings = Settings()
         self._dut_controllers: list[DeviceTabController] = []
         self._next_dut_num = 1
+        self._settings_applied = False
 
         add_btn = QToolButton()
         add_btn.setText("+")
-        add_btn.setToolTip("Add DUT tab (Ctrl+T)")
+        add_btn.setToolTip("Add DUT tab (Ctrl+N)")
         add_btn.clicked.connect(self._add_dut_tab_auto)
         self._tabs.setCornerWidget(add_btn, Qt.TopLeftCorner)
 
@@ -61,21 +61,28 @@ class MainWindow(QMainWindow):
         else:
             self._add_dut_tab("dut_1", "DUT 1")
 
+    def showEvent(self, event) -> None:  # noqa: N802
+        super().showEvent(event)
+        if not self._settings_applied:
+            self._settings_applied = True
+            self._apply_settings()
+
     def _build_menu_bar(self) -> None:
         mb = self.menuBar()
 
         view_menu = mb.addMenu("&View")
-        view_menu.addAction("New Tab", self._add_dut_tab_auto, QKeySequence("Ctrl+T"))
+        view_menu.addAction("New Tab\tCtrl+N", self._add_dut_tab_auto)
-        view_menu.addAction("Close Tab", self._close_current_tab, QKeySequence("Ctrl+W"))
+        view_menu.addAction("Close Tab\tCtrl+W", self._close_current_tab)
         view_menu.addSeparator()
-        view_menu.addAction("Clear Log", self._clear_current_log, QKeySequence("Ctrl+L"))
+        view_menu.addAction("Clear Log\tCtrl+C", self._clear_current_log)
-        view_menu.addAction("Find", self._focus_find, QKeySequence("Ctrl+F"))
+        view_menu.addAction("Find\tCtrl+S", self._focus_find)
 
         settings_menu = mb.addMenu("&Settings")
         settings_menu.addAction("Preferences...", self._open_settings)
 
         help_menu = mb.addMenu("&Help")
         help_menu.addAction("About", self._show_about)
+        help_menu.addAction("Shortcuts", self._show_shortcuts)
 
     def _toggle_theme(self) -> None:
         if self._current_palette.name == "light":
@@ -87,6 +94,15 @@ class MainWindow(QMainWindow):
         for ctrl in self._dut_controllers:
             ctrl.view.log_view.set_colors(p.log_rx, p.log_tx, p.log_info)
 
+    def _toggle_connect(self) -> None:
+        ctrl = self._current_controller()
+        if ctrl:
+            ctrl.view.connect_button.click()
+
+    def _show_shortcuts(self) -> None:
+        text = "\n".join(f"Ctrl+{lbl}\t{desc}" for lbl, desc in self._shortcut_labels)
+        QMessageBox.information(self, "Shortcuts", text)
+
     def _show_about(self) -> None:
         QMessageBox.about(self, config.APP_NAME,
                           f"{config.APP_NAME}\n"
@@ -96,14 +112,34 @@ class MainWindow(QMainWindow):
                           f"Licensed under the Apache License, Version 2.0\n"
                           f"All rights reserved. For internal use only.")
 
+    _KEY_EVENTS = frozenset({QEvent.KeyPress, QEvent.ShortcutOverride})
+
     def _setup_shortcuts(self) -> None:
-        QShortcut(QKeySequence("Ctrl+T"), self, activated=self._add_dut_tab_auto)
+        bindings = (
-        QShortcut(QKeySequence("Ctrl+W"), self, activated=self._close_current_tab)
+            ("N", "New DUT tab", Qt.Key_N, self._add_dut_tab_auto),
-        QShortcut(QKeySequence("Ctrl+F"), self, activated=self._focus_find)
+            ("W", "Close current tab", Qt.Key_W, self._close_current_tab),
-        QShortcut(QKeySequence("Ctrl+L"), self, activated=self._clear_current_log)
+            ("D", "Connect / Disconnect", Qt.Key_D, self._toggle_connect),
-        QShortcut(QKeySequence("Ctrl+Return"), self, activated=self._send_current)
+            ("S", "Find in log", Qt.Key_S, self._focus_find),
-        QShortcut(QKeySequence("Ctrl+Shift+F"), self, activated=self._flash_current)
+            ("C", "Clear log", Qt.Key_C, self._clear_current_log),
-        QShortcut(QKeySequence("Ctrl+R"), self, activated=self._reset_current)
+            ("Enter", "Send command", Qt.Key_Return, self._send_current),
+            ("F", "Flash firmware", Qt.Key_F, self._flash_current),
+            ("R", "Normal mode", Qt.Key_R, self._reset_current),
+        )
+        self._shortcut_labels = tuple((lbl, desc) for lbl, desc, _, _ in bindings)
+        self._key_map = {key: handler for _, _, key, handler in bindings}
+        QApplication.instance().installEventFilter(self)
+
+    def eventFilter(self, obj, event) -> bool:
+        etype = event.type()
+        if etype in self._KEY_EVENTS and event.modifiers() == Qt.ControlModifier:
+            handler = self._key_map.get(event.key())
+            if handler:
+                if etype == QEvent.ShortcutOverride:
+                    event.accept()
+                    return True
+                handler()
+                return True
+        return super().eventFilter(obj, event)
 
     def _close_current_tab(self) -> None:
         self._close_tab(self._tabs.currentIndex())
@@ -146,8 +182,7 @@ class MainWindow(QMainWindow):
     def _reset_current(self) -> None:
         ctrl = self._current_controller()
         if ctrl:
-            from ameba_control_panel.config import Mode
+            ctrl.flash.run_mode(Mode.NORMAL)
-            ctrl.flash.run_mode(Mode.RESET)
 
     def _current_controller(self) -> DeviceTabController | None:
         widget = self._tabs.currentWidget()