refactor: relocate live stream controls to ReadoutPanel and update chart axis rendering

src/pygui/backend/visualization/trend_chart_item.py

@@ -44,6 +44,11 @@ class TrendChartItem(QQuickPaintedItem):
 
         self._data: list[float] = []
         self._padding: int = 8
+        # Separate from `_padding` (breathing room around the plot area): these
+        # reserve space for the axis labels themselves, which are wider than
+        # `_padding` alone — that mismatch is what clipped y-axis text before.
+        self._margin_left: int = 34
+        self._margin_bottom: int = 16
         self._line_color = QColor("#5B9DF5")
         self._grid_color = QColor("#2A3441")
         self._text_color = QColor("#CBD5E1")
@@ -153,9 +158,11 @@ class TrendChartItem(QQuickPaintedItem):
         if w <= 0 or h <= 0:
             return
 
-        plot_rect = QRectF(self._padding, self._padding,
-                           max(1, w - 2 * self._padding),
-                           max(1, h - 2 * self._padding))
+        left = self._padding + self._margin_left
+        bottom_inset = self._padding + self._margin_bottom
+        plot_rect = QRectF(left, self._padding,
+                           max(1, w - left - self._padding),
+                           max(1, h - self._padding - bottom_inset))
 
         self._draw_grid(painter, plot_rect)
 
@@ -220,16 +227,36 @@ class TrendChartItem(QQuickPaintedItem):
         font = QFont(painter.font())
         font.setPointSizeF(max(7.0, font.pointSizeF() * 0.85))
         painter.setFont(font)
+
         rows = 4
+        label_w = self._margin_left - 4  # 4px gutter before the plot area
         for i in range(rows + 1):
             t = i / rows
             y_val = y_max - t * (y_max - y_min)
             y_px = plot_rect.top() + t * plot_rect.height()
             label = f"{y_val:.1f}"
-            painter.drawText(QRectF(0, y_px - 7, self._padding, 14),
+            painter.drawText(QRectF(0, y_px - 7, label_w, 14),
                              Qt.AlignmentFlag.AlignRight | Qt.AlignmentFlag.AlignVCenter,
                              label)
 
+        # X-axis: sample index. `trendData` carries plain averages with no
+        # timestamps attached, so index is the only x-coordinate available —
+        # it reads correctly for review mode (index == frame number) and as a
+        # relative recency order for the live rolling window. paint() already
+        # guarantees len(self._data) >= 2 before calling this.
+        n = len(self._data)
+        cols = min(4, n - 1)
+        y_px = plot_rect.bottom() + 4
+        for i in range(cols + 1):
+            idx = round((i / cols) * (n - 1))
+            x_px = self._x_to_px(idx, n, plot_rect)
+            align = (Qt.AlignmentFlag.AlignLeft if i == 0
+                     else Qt.AlignmentFlag.AlignRight if i == cols
+                     else Qt.AlignmentFlag.AlignHCenter)
+            painter.drawText(QRectF(x_px - 20, y_px, 40, 14),
+                             align | Qt.AlignmentFlag.AlignTop,
+                             str(idx))
+
     def _draw_line(
         self,
         painter: QPainter,