GUI v0.2.13: chart Y-axis range control (right-edge dual-handle slider)

- TemperatureChart gains a right-edge slider on a FIXED -20..120C rail
  (user-specified): top handle = upper bound, bottom handle = lower bound,
  drag middle band = pan keeping span, click free rail = snap that bound.
  First drag engages manual mode (yManualEngaged -> sync button state +
  config); release quantizes to 0.1C via yRangeChanged, min span 0.5C.
  Bound values during drag must come from live display range, not the
  stale paint cache (two drags without repaint made pan jump the range).
- Auto/manual toggle moved into the card header (was a wrapped second
  row); pause/clear merged into header too; legend moved to top-left.
- Value labels next to handles only visible on hover/drag (constant
  labels covered the curve per user feedback).
- Out-of-range curves clipped back to the plot area (setClipRect);
  current-value marker suppressed outside the manual range.
- Draft textbox rows from v0.2.10 superseded; versions v0.2.10..v0.2.13.
- Fixed "no data yet" hint never disappearing: set_source cached a
  stale _has_data bool once at build time while data flows through the
  same list references; now evaluated live at paint time.
- config: y_axis key persists mode/bounds; invalid stored values fall
  back to auto. selftest settings isolated to a temp dir (user json with
  stored manual state broke the fresh-default assertions).
- selftest_gui: slider hit/drag/clamp/pan/clipping regression + hint
  gating; 83 checks all pass.

GUI/config.py

@@ -32,6 +32,9 @@ SERIAL_CFG = {'port': '', 'baud': filmforge_rs485.DEFAULT_BAUD,
 REPORT_MS = 500               # 上报间隔输入框默认值
 WINDOW_SEC = DEFAULT_WINDOW_SEC
 THEME = 'System'
+Y_MODE = 'auto'               # 曲线 Y 轴(温度轴): 'auto'=自适应 / 'manual'=固定范围
+Y_MIN = None                  # 手动 Y 轴上下限(℃), 仅 Y_MODE='manual' 且合法时生效
+Y_MAX = None
 
 
 def load_settings():
@@ -68,6 +71,19 @@ def load_settings():
     theme = str(data.get('theme') or '')
     if theme in ('Dark', 'Light', 'System'):
         THEME = theme
+    ax = data.get('y_axis')
+    if isinstance(ax, dict):
+        mode = str(ax.get('mode') or '')
+        if mode in ('auto', 'manual'):
+            globals()['Y_MODE'] = mode
+        try:
+            globals()['Y_MIN'] = round(float(ax.get('min')), 2)
+        except (TypeError, ValueError):
+            pass
+        try:
+            globals()['Y_MAX'] = round(float(ax.get('max')), 2)
+        except (TypeError, ValueError):
+            pass
 
 
 def save_settings():
@@ -77,6 +93,7 @@ def save_settings():
         'report_ms': REPORT_MS,
         'window_sec': WINDOW_SEC,
         'theme': THEME,
+        'y_axis': {'mode': Y_MODE, 'min': Y_MIN, 'max': Y_MAX},
     }
     try:
         with open(SETTINGS_FILE, 'w', encoding='utf-8') as f: