界面：三维面板只留画面与图例，全部配置进「三维显示设置」对话框；三维占比提为最宽

- What（隐藏配置）: `ThreeDPanel` 把**所有设置**收进一个块
  （`controls_widget`：总开关、观察方向、显示外壳、放大形变+增益、色标模式与范围、显示帧率、
  复位按钮、显示统计），面板本身只保留读图需要的东西：色条 + 一行紧凑图例（数量/自动色标范围/
  来源）+ 状态行。新增 `scene3d/settings_dialog.py` 的 `Scene3dSettingsDialog`：非模态
  （调参时画面还在动），承载的就是面板那套控件本身（同一批 widget，信号通路不变），
  关闭只是隐藏（控件必须活着，下一次读设置还要用）。
  两个入口：视图菜单新增 `三维显示设置…`（`act_scene3d_settings` → `Mesh3dPanel.open_settings()`）
  与面板标题栏的齿轮；无三维可配时（box 传感器 / 无 GL / 无场景包）菜单项会把面板上的原因
  原样提示出来，而不是弹一个空对话框。标题栏另有「复位视角」图标（新画的 `reset_view` 图标，
  环形箭头，随主题着色）。
- What（提高占比）: live/replay 预设把三维面板设为最宽：`VIEW_SPLITTER_SIZES` (620, 300, 520)、
  `DEFAULT_SPLITTER_SIZES` (620, 320, 500)、`DEFAULT_3D_PANE_WIDTH` 340 → 620、
  `MIN_PANEL_WIDTHS["mesh3d"]` 260 → 200（面板里没有表单要放了，画面才是重点）、
  `ViewLayoutController.apply_panel_visibility` 的拉伸权重 2 → 5（2D 3、曲线 4）。
  1440×880 实测：三维约 430 px（原约 280）、2D 约 265、曲线约 320。
- What（拍视频/评审用）: `tools/ui_snapshot.py` 新增 `--scene flow3d`：驱动一批**带真实光流场**的
  packets（适配器只接受声明了 provenance 的字段），所以三维面板真的有颜色、曲线也真的在动；
  这是本次界面评审与演示视频的取景脚本。配 `--sensor finger --panels 3d --preset live`。
- What（测试）: 新增 `apps/studio/tests/test_scene3d_pane_ui.py`（5 项）：面板只有图例没有设置、
  对话框承载的是面板自己的控件且设置信号照旧、关闭只隐藏不销毁、标题栏两个动作可用、
  无场景时 `open_settings()` 返回 False、`reset_view` 转发、`reset_view` 图标两种主题都能画、
  视图菜单项能打开对话框（无 GL 时给原因）。`test_view_layout.py` 增一条"出厂 live 布局里
  三维最宽"的断言（并更正我自己那条 340 的旧期望）。
- 文档: `studio-3d-stages.md` 的「尚未完成」第 1 条（阶段 8 第二批）改写为"部分已做"，
  写清已完成的部分与仍留后的四项（页签容器/窄窗口回退/曲线量程开关/独立诊断抽屉）。
- Why: 三维面板原来下半屏全是表单，画面被挤成一小块——拍视频要的是"三维是主角"。
  配置不是不需要，而是不该和画面抢地方；放进对话框后画面变大、参数反而更好找（一处看全）。
- Verification: pytest shared/tests apps/studio/tests（offscreen）650 passed / **2 failed** / 15 skipped，
  两个失败都是 `shared/tests/test_worker_frame_rate.py` 的**墙钟计时**用例（30 fps 设备被测成
  24–25 fps）：已在 `d539ce9` 的干净 worktree 上复现同样的失败，属本机负载（DSH/Cursor/飞书 占 CPU）
  而非本次改动；真 GL 用例 `test_scene3d_gl_smoke` + `test_scene3d_view` 61 项 0 失败（1 跳过）；
  `tools/ui_check.py` 587 项检查 0 失败；`.repro/locale_check.py` 0 缺失（新增 6 个 key 双语齐备）。
  目视验收：`--scene flow3d` 渲染的 1440×880 截图（拆分前后各一张）见提交说明附言。
- Not in this change: 不改三维渲染/契约/记录；不做页签容器与窄窗口回退；
  曲线量程仍是出厂 ±20 N（演示取景脚本会临时调窄，产品默认值另议）。

apps/studio/tools/ui_snapshot.py

@@ -147,6 +147,112 @@ def _run_scene(window, app, scene: str):
         app.processEvents()
 
 
+def _flow_scene(window, app, *, frames: int = 240) -> None:
+    """Drive a synthetic session whose frames carry a real optical-flow field.
+
+    The 3D pane is coloured by the frame's *own* flow (see
+    ``orisys_studio.scene3d.adapters``): a packet that does not state one is refused,
+    so a picture with colour needs packets that do. This is the scene the interface is
+    reviewed from — the real widgets, the real renderer, the real adapter, and a field
+    shaped like a pressed fingertip (strongest at the centre, fading to the rim).
+    """
+    import time as _time
+
+    import numpy as np
+    from orisys_app_shared.acquisition.sdk_worker import SdkPacket
+
+    from ui_check import _StuckWorker
+
+    stuck = _StuckWorker()
+    window._ensure_workers = lambda: None
+    window._box_worker = stuck
+    window._finger_worker = stuck
+    window.toolbar.btn_run.setChecked(True)
+    for _ in range(4):
+        app.processEvents()
+
+    # The unrolled finger domain: 280x300, which is the grid the scene's UV island
+    # uses. The flow is already unrolled, so the adapter is given no remap.
+    height, width = 300, 280
+    grid_y, grid_x = np.mgrid[0:height, 0:width].astype(np.float32)
+    centre_y, centre_x = height * 0.52, width / 2.0
+    dy, dx = grid_y - centre_y, grid_x - centre_x
+    radius = np.sqrt(dx * dx + dy * dy) + 1e-3
+    profile = np.exp(-((radius / (width * 0.30)) ** 2)).astype(np.float32)
+    flow = np.stack(
+        [dx / radius * profile * 7.0, dy / radius * profile * 7.0], axis=-1
+    ).astype(np.float32)
+    # A recognisable camera image as well, so the 2D panel is not black next to it.
+    frame = np.zeros((height, width, 3), np.uint8)
+    frame[..., 1] = (40.0 + profile * 150.0).astype(np.uint8)
+    frame[..., 2] = (profile * 90.0).astype(np.uint8)
+
+    for index in range(frames):
+        # The forces move: a flat line reads as "the demo is not running", and the
+        # charts are half of what the video has to show.
+        phase = index / 30.0
+        # A period of a couple of seconds, so the trace visibly moves inside the chart's
+        # rolling window instead of looking like a slow ramp.
+        normal = 3.4 + 2.4 * math.sin(phase * 2.4)
+        shear_x = 1.6 * math.sin(phase * 3.1 + 0.4)
+        shear_y = -1.3 * math.cos(phase * 2.7)
+        stuck.emit(
+            SdkPacket(
+                raw_frame=frame,
+                processed_frame=frame,
+                flow=flow,
+                timestamp=1000.0 + index / 30.0,
+                mono_t=float(index) / 30.0,
+                fps=30.0,
+                process_ms=6.0,
+                capture_fps=30.0,
+                session_id=1,
+                frame_id=index,
+                valid=True,
+                raw_available=True,
+                normal_force=normal,
+                shear_x=shear_x,
+                shear_y=shear_y,
+                normal_force_raw=9.0 + index * 0.1,
+                shear_x_raw=0.4,
+                shear_y_raw=-0.4,
+                force_unit="N",
+                force_calibrated=True,
+                calibrated_axes=("fn", "fx", "fy"),
+                flow_valid=True,
+                flow_frame_id=index,
+                depth_valid=None,
+                depth_frame_id=None,
+                forces_valid=True,
+            )
+        )
+        # The window's own presenter runs *while* the frames arrive, the way it does in
+        # a session: the charts then hold a real time series instead of one sample.
+        if index % 4 == 0:
+            window._on_run_tick()
+            app.processEvents()
+
+    # The 3D picture is composed on the view's own worker and taken one finished frame
+    # at a time by the run timer, so pump both until something has actually been shown.
+    view = window.mesh3d_panel.view
+    deadline = _time.perf_counter() + 20.0
+    while _time.perf_counter() < deadline:
+        window._on_run_tick()
+        app.processEvents()
+        if view is not None and view.render_totals().get("shown", 0) > 0:
+            break
+        _time.sleep(0.01)
+    window._run_timer.stop()
+    # The overview strip is rebuilt at most once a second (it is a whole-session
+    # decimation) and this scene fills eight seconds of session in well under that, so
+    # it is rebuilt once here — the same thing ``_demo_data`` does for the same reason.
+    window.force_plots._overview_dirty = True
+    window.force_plots._last_overview_at = 0.0
+    window.force_plots._sync_overview()
+    for _ in range(6):
+        app.processEvents()
+
+
 def _demo_data(window) -> None:
     """Fill the plots, the calibration table and the arrow canvas."""
     from orisys_app_shared.force.session import SessionSample, SessionStore
@@ -242,14 +348,16 @@ def main() -> int:
     parser.add_argument("--demo", action="store_true", help="inject demo plot/table data")
     parser.add_argument(
         "--scene",
-        choices=("idle", "connecting", "recording", "replay"),
+        choices=("idle", "connecting", "recording", "replay", "flow3d"),
         default="idle",
         help=(
             "connecting renders the Stop/cancel state of a hung device open; "
             "recording renders the record strip of a running recording "
             "(mocked stats: no file is written, no device is opened); "
             "replay writes one short synthetic recording and opens it in the "
-            "replay view so the progress bar can be reviewed"
+            "replay view so the progress bar can be reviewed; "
+            "flow3d drives packets that carry a real optical-flow field, which is "
+            "what colours the 3D pane (use with --sensor finger --panels 3d)"
         ),
     )
     parser.add_argument(
@@ -317,7 +425,10 @@ def main() -> int:
     if args.scene == "replay":
         _run_scene(window, app, "replay")
 
-    if args.demo and args.scene != "replay":
+    if args.scene == "flow3d":
+        _flow_scene(window, app)
+
+    if args.demo and args.scene not in ("replay", "flow3d"):
         _demo_data(window)
         for _ in range(4):
             app.processEvents()