UI: streamline Add Device dialog and serial config widget

Add Device dialog:
- Replace Available Devices QGroupBox with plain devWindowTitle label
  to match Configuration section style — no box/border
- Auto-scan on open via QTimer.singleShot(0)
- Rename Scan All → Refresh

Serial config widget:
- Fix gap between protocol panel and Available Serial Ports: introduce
  _AdaptiveStack (QStackedWidget subclass) that reports only the current
  panel's sizeHint; set Fixed vertical size policy so the stack never
  expands beyond its content regardless of window size
- Stretch added between Available Serial Ports and Apply & Reconnect so
  the button stays pinned to the bottom
- Rename Channels → Signals in _GenericPanel and _SCPIPanel (Signal Queries)

Config dialog (device info tab):
- Rename Channels → Signals

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 36 insertions, 5 deletions

diff --git a/devices/serial_device.py b/devices/serial_device.py
index 78f74a2..c3ce65f 100644
--- a/devices/serial_device.py
+++ b/devices/serial_device.py
@@ -27,7 +27,7 @@ from PyQt6.QtCore import Qt, QThread, pyqtSignal
 from PyQt6.QtWidgets import (
     QCheckBox, QComboBox, QDoubleSpinBox, QFormLayout, QGroupBox,
     QHBoxLayout, QHeaderView, QLabel, QLineEdit, QListWidget,
-    QListWidgetItem, QPushButton, QScrollArea, QSpinBox,
+    QListWidgetItem, QPushButton, QScrollArea, QSizePolicy, QSpinBox,
     QStackedWidget, QTableWidget, QTableWidgetItem, QVBoxLayout, QWidget,
 )
 
@@ -359,6 +359,30 @@ class SerialDevice(BaseDevice):
 
 # ── Config widget ─────────────────────────────────────────────────────────────
 
+class _AdaptiveStack(QStackedWidget):
+    """QStackedWidget sized to its current panel only — no gap from hidden panels."""
+
+    def _current_height(self) -> int:
+        w = self.currentWidget()
+        if not w:
+            return 0
+        lyt = w.layout()
+        if lyt:
+            m = lyt.contentsMargins()
+            return lyt.sizeHint().height() + m.top() + m.bottom()
+        return w.sizeHint().height()
+
+    def sizeHint(self):
+        from PyQt6.QtCore import QSize
+        h = self._current_height()
+        w = self.currentWidget()
+        sw = w.sizeHint().width() if w else super().sizeHint().width()
+        return QSize(sw, h) if h > 0 else super().sizeHint()
+
+    def minimumSizeHint(self):
+        return self.sizeHint()
+
+
 class SerialConfigWidget(QWidget):
     def __init__(self, device: SerialDevice):
         super().__init__()
@@ -400,7 +424,7 @@ class SerialConfigWidget(QWidget):
         root.addWidget(conn_grp)
 
         # ── Protocol-specific settings (stacked) ──────────────────────────
-        self._proto_stack = QStackedWidget()
+        self._proto_stack = _AdaptiveStack()
         self._generic_panel  = _GenericPanel(device=self.device)
         self._scpi_panel     = _SCPIPanel(device=self.device)
         self._modbus_panel   = _ModbusPanel(device=self.device)
@@ -410,6 +434,10 @@ class SerialConfigWidget(QWidget):
                       self._modbus_panel, self._mark10_panel, self._cml_panel):
             self._proto_stack.addWidget(panel)
         self._proto_stack.setCurrentIndex(_STACK_IDX.get(self.device._fmt, 0))
+        sp = self._proto_stack.sizePolicy()
+        sp.setVerticalPolicy(QSizePolicy.Policy.Fixed)
+        self._proto_stack.setSizePolicy(sp)
+        self._proto_stack.currentChanged.connect(self._fix_stack_height)
         root.addWidget(self._proto_stack)
 
         # ── Port scanner ───────────────────────────────────────────────────
@@ -436,13 +464,16 @@ class SerialConfigWidget(QWidget):
         scan_lay.addWidget(self._port_list)
         scan_lay.addWidget(hint)
         root.addWidget(scan_grp)
+        root.addStretch()
 
         # ── Apply ──────────────────────────────────────────────────────────
         apply_btn = QPushButton("Apply & Reconnect")
         apply_btn.setObjectName("applyButton")
         apply_btn.clicked.connect(self._apply)
         root.addWidget(apply_btn)
-        root.addStretch()
+
+    def _fix_stack_height(self, _: int):
+        self._proto_stack.updateGeometry()
 
     def _on_fmt_changed(self, _):
         fmt = _FORMAT_LABELS.get(self._fmt_cb.currentText(), "key:val")
@@ -513,7 +544,7 @@ class _GenericPanel(QWidget):
         self._ch_spin = QSpinBox()
         self._ch_spin.setRange(1, 32)
         self._ch_spin.setValue(len(device.info.channels) if device._fmt in _GENERIC_FORMATS else 4)
-        lay.addRow("Channels:", self._ch_spin)
+        lay.addRow("Signals:", self._ch_spin)
 
     def collect(self) -> dict:
         return {"num_channels": self._ch_spin.value()}
@@ -529,7 +560,7 @@ class _SCPIPanel(QWidget):
         lay.setContentsMargins(0, 4, 0, 4)
         lay.setSpacing(6)
 
-        grp = QGroupBox("Channel Queries")
+        grp = QGroupBox("Signal Queries")
         grp_lay = QVBoxLayout(grp)
 
         self._table = QTableWidget()