补齐 Autocal 测点质量与独立 trial 验证

按已确认窗口比较重复性、加载卸载差异和零载恢复，并逐 trial 留出验证。55 项定向测试、已录视频复核闭环及代码文档检查通过。

apps/autocal/config/locales/en_US.json

@@ -490,6 +490,40 @@
     "depth_missing": "No valid depth/deformation for this frame",
     "flow_missing": "No valid displacement for this frame"
   },
+  "quality": {
+    "open": "Repeatability and validation…",
+    "title": "Site quality analysis",
+    "notice": "Only operator-confirmed valid windows are used. Results remain exploratory. Replay, stability review and trial holdout do not establish physical accuracy or reference synchronisation.",
+    "repeatability": "Repeatability",
+    "repeatability_note": "For the same branch and exact declared reference force, average within each trial, then report range and sample standard deviation across trials. At least two trials are required; this differs from within-hold variation.",
+    "hysteresis": "Loading/unloading difference",
+    "hysteresis_note": "Pair nonzero loading and unloading windows at exactly the same declared reference force within one trial, without interpolation. Difference is unloading minus loading, in raw units; unmatched levels produce no result.",
+    "zero_return": "Zero return",
+    "zero_return_note": "Final unloaded zero minus initial zero in the same trial, in raw units. Only confirmed windows declaring 0 N are paired.",
+    "validation": "Held-out trial validation",
+    "validation_note": "Hold out each entire trial, fit zero/loading windows from other trials, then predict all confirmed windows in the held-out trial. Windows have equal weight. Cross-validation does not replace another independent experiment.",
+    "validation_summary": "Evaluated windows: {count}; RMSE {rmse} N; MAE {mae} N; maximum absolute error {maximum} N; outside training raw range: {outside}.",
+    "no_data": "No eligible data yet; review the required windows first.",
+    "insufficient_training": "Insufficient training data in other trials",
+    "outside_range": "Outside training raw range",
+    "in_range": "Within training raw range",
+    "col_branch": "Phase",
+    "col_load": "Manual reference (N)",
+    "col_trials": "Trials",
+    "col_range": "Between-trial range (raw)",
+    "col_std": "Between-trial sample std (raw)",
+    "col_trial": "Trial",
+    "col_load_raw": "Loading mean (raw)",
+    "col_unload_raw": "Unloading mean (raw)",
+    "col_delta_raw": "Difference (raw)",
+    "col_initial_zero": "Initial zero (raw)",
+    "col_final_zero": "Final zero (raw)",
+    "col_held_out": "Held-out trial",
+    "col_training": "Training trials",
+    "col_predicted": "Predicted force (N)",
+    "col_error": "Prediction minus reference (N)",
+    "col_range_status": "Range/status"
+  },
   "review": {
     "load_selection": "Load saved review…",
     "confirm_stable": "Reviewed as stable",