三维设置加箭头阈值，静默处理网格冲突

对话框写回 flow_on_px（二维三维共用），去掉 analysis_grid_mismatch 告警，缩短 UV/形变等工程腔文案并认 source=analysis。已用 pane UI 与 controller 单测验证。

apps/studio/config/locales/en_US.json

@@ -225,7 +225,7 @@
     "depth_unavailable": "No depth data for this frame",
     "depth_scale": "Depth scale {low} – {high}",
     "arrow_scale": "Arrows: displacement ×{factor}",
-    "arrow_scale_tip": "Display magnification of the relative displacement: the arrows are drawn from the algorithm output of the captured image, with the measured displacement multiplied by this factor and capped at 0.8 of the grid spacing (a capped arrow no longer shows its true factor).",
+    "arrow_scale_tip": "Arrow length is magnified by displacement.",
     "arrow_pipeline": "Captured image → algorithm output",
     "arrow_pipeline_tip": "Arrows are drawn over the algorithm output, not over the raw camera frame: points below the threshold get no arrow",
     "arrow_area_masked": "Valid area",
@@ -315,7 +315,6 @@
     "analysis_cancelled": "the analysis was cancelled: no complete result was written, so no playback is served",
     "analysis_no_source": "this recording has no video segment to analyse",
     "analysis_busy": "an analysis is already running: wait for it, or cancel it",
-    "analysis_grid_mismatch": "the current display settings moved the sample grid ({keys}); the stored candidate locations cannot serve it, so the replay keeps drawing the result's own grid",
     "analysis_no_chain": "this recording does not say which sensor and configuration produced it ({error}), so no result can be read and no pass can be run",
     "analysis_setup_declined": "no analysis was set up for this video: the setup prompt was dismissed, so there is nothing to draw from. Use Analysis ▸ Analysis setup… or open the video again"
   },
@@ -504,7 +503,7 @@
     "housing": "Housing",
     "deform": "Exaggerate",
     "deform_tip": "Display-only magnification of the measured deformation. It changes the picture and nothing else: the recorded data, the calibration and the camera are not touched.",
-    "deform_unavailable": "This data source provides no 3D displacement: the pane can only colour the surface, so exaggeration is unavailable.",
+    "deform_unavailable": "This data has no 3D displacement; exaggeration is unavailable.",
     "field": "Colour by",
     "field_tip": "Colour the surface by depth or optical flow.",
     "field_depth": "Depth response",
@@ -512,10 +511,12 @@
     "field_substituted": "This frame shows {shown}, not the chosen {chosen}.",
     "flow_arrows": "Surface flow arrows",
     "flow_arrows_tip": "Draw optical-flow arrows on the sensing surface using the same sample points as the 2D view.",
-    "flow_arrows_unavailable": "This scene package has no UV→scene surface mapping, so flow arrows cannot be drawn.",
+    "flow_arrows_unavailable": "This scene cannot draw flow arrows.",
     "contact_arrow": "Contact normal arrow",
     "contact_arrow_tip": "Draw a yellow local-normal arrow at the contact centre (length from the normal response, capped — not a calibrated force vector).",
-    "contact_arrow_unavailable": "This scene package has no UV→scene surface mapping, so the contact arrow cannot be drawn.",
+    "contact_arrow_unavailable": "This scene cannot draw the contact arrow.",
+    "flow_threshold": "Arrow threshold",
+    "flow_threshold_tip": "Arrows below this displacement (px) are not drawn; shared by 2D and 3D.",
     "quantity_flow_magnitude": "Optical flow magnitude",
     "quantity_depth_response": "Depth response",
     "preset_default": "Default view",
@@ -556,9 +557,9 @@
     "severity_info": "Note",
     "severity_warning": "Warning",
     "severity_error": "Error",
-    "stats": "shown {displayed} · display drops {dropped} · compose {compose} ms · paint {paint} ms",
-    "source_analysis": "Analysis result: one finished pass, read by frame",
-    "source_analysis_tip": "The picture comes from a stored analysis result: the chain has already run and its output is on disk, so scrubbing and playing are file reads. Changing a threshold or a colour does not recompute."
+    "stats": "shown {displayed} · frames not shown in time {dropped} · compose {compose} ms · paint {paint} ms",
+    "source_analysis": "Analysis result: read by frame",
+    "source_analysis_tip": "The picture comes from a stored analysis result. Changing a threshold or colour does not recompute."
   },
   "analysis": {
     "title": "Analysing the recording",