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>

2 files changed, 12 insertions, 10 deletions

diff --git a/ui/add_device_dialog.py b/ui/add_device_dialog.py
index f0cbde1..2956a96 100644
--- a/ui/add_device_dialog.py
+++ b/ui/add_device_dialog.py
@@ -8,7 +8,7 @@ from PyQt6.QtWidgets import (
     QDialog, QVBoxLayout, QHBoxLayout, QFormLayout,
     QComboBox, QLineEdit, QSpinBox, QDoubleSpinBox,
     QCheckBox, QPushButton, QLabel, QMessageBox,
-    QStackedWidget, QWidget, QGroupBox, QListWidget,
+    QStackedWidget, QWidget, QListWidget,
     QListWidgetItem, QFrame, QSizePolicy,
 )
 from PyQt6.QtCore import Qt, QThread, pyqtSignal
@@ -58,10 +58,10 @@ class _DeviceListScanner(QWidget):
         lay.setSpacing(4)
 
         top = QHBoxLayout()
-        self._scan_btn = QPushButton("🔍  Scan All")
+        self._scan_btn = QPushButton("🔍  Refresh")
         self._scan_btn.setObjectName("addTraceBtn")
         self._scan_btn.clicked.connect(self.scan_all)
-        self._status = QLabel("Click Scan to detect devices")
+        self._status = QLabel("Scanning…")
         self._status.setObjectName("traceSource")
         top.addWidget(self._scan_btn)
         top.addWidget(self._status, 1)
@@ -248,13 +248,13 @@ class AddDeviceDialog(QDialog):
         root.addWidget(_divider())
 
         # ── Available Devices ─────────────────────────────────────────────
-        avail_grp = QGroupBox("Available Devices")
-        avail_lay = QVBoxLayout(avail_grp)
-        avail_lay.setSpacing(6)
+        avail_hdr = QLabel("Available Devices")
+        avail_hdr.setObjectName("devWindowTitle")
+        root.addWidget(avail_hdr)
 
         self._scanner = _DeviceListScanner()
         self._scanner.device_selected.connect(self._on_device_selected)
-        avail_lay.addWidget(self._scanner)
+        root.addWidget(self._scanner)
 
         conn_form = QFormLayout()
         conn_form.setSpacing(6)
@@ -278,8 +278,7 @@ class AddDeviceDialog(QDialog):
         self._sim_chk = QCheckBox("Simulation mode")
         conn_form.addRow(self._sim_chk)
 
-        avail_lay.addLayout(conn_form)
-        root.addWidget(avail_grp)
+        root.addLayout(conn_form)
 
         root.addWidget(_divider())
 
@@ -331,6 +330,9 @@ class AddDeviceDialog(QDialog):
 
         self._on_type_changed(0)
 
+        from PyQt6.QtCore import QTimer
+        QTimer.singleShot(0, self._scanner.scan_all)
+
     # ── Handlers ──────────────────────────────────────────────────────────
 
     def _on_device_selected(self, kind: str, value):
diff --git a/ui/config_dialog.py b/ui/config_dialog.py
index bafac24..d9bc9df 100644
--- a/ui/config_dialog.py
+++ b/ui/config_dialog.py
@@ -66,5 +66,5 @@ class DeviceConfigDialog(QDialog):
         form.addRow("Model:",        _ro(info.model))
         form.addRow("Version:",      _ro(info.version))
         form.addRow("Status:",       _ro(self.device.status.value))
-        form.addRow("Channels:",     _ro(len(info.channels)))
+        form.addRow("Signals:",      _ro(len(info.channels)))
         return w