Skip motion threshold configuration (#22255)

* backend

* frontend

* i18n

* docs

* add test

* clean up

* clean up motion detection docs

* formatting

* make optional

frigate/config/camera/motion.py

@@ -24,10 +24,17 @@ class MotionConfig(FrigateBaseModel):
     lightning_threshold: float = Field(
         default=0.8,
         title="Lightning threshold",
-        description="Threshold to detect and ignore brief lighting spikes (lower is more sensitive, values between 0.3 and 1.0).",
+        description="Threshold to detect and ignore brief lighting spikes (lower is more sensitive, values between 0.3 and 1.0). This does not prevent motion detection entirely; it merely causes the detector to stop analyzing additional frames once the threshold is exceeded. Motion-based recordings are still created during these events.",
         ge=0.3,
         le=1.0,
     )
+    skip_motion_threshold: Optional[float] = Field(
+        default=None,
+        title="Skip motion threshold",
+        description="If set to a value between 0.0 and 1.0, and more than this fraction of the image changes in a single frame, the detector will return no motion boxes and immediately recalibrate. This can save CPU and reduce false positives during lightning, storms, etc., but may miss real events such as a PTZ camera auto‑tracking an object. The trade‑off is between dropping a few megabytes of recordings versus reviewing a couple short clips. Leave unset (None) to disable this feature.",
+        ge=0.0,
+        le=1.0,
+    )
     improve_contrast: bool = Field(
         default=True,
         title="Improve contrast",