add help docs and ?

docs/nodes/Scar Removal.md

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+# Scar Removal
+
+Detect and remove horizontal scan scars using Gwyddion-derived scar marking thresholds, then interpolate over the detected mask with a Laplace-style inpaint.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field with scan scars |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| corrected | DATA_FIELD | Field with scars removed and interpolated |
+| scar_mask | IMAGE | Binary mask of the detected scar pixels |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| scar_type | dropdown | both | Which scar polarity to detect: both, positive (bright), or negative (dark) |
+| threshold_high | FLOAT | 0.666 | High threshold relative to local RMS for strong scar detection (0–2) |
+| threshold_low | FLOAT | 0.25 | Low threshold for extending already-detected scars (0–2) |
+| min_length | INT | 16 | Minimum horizontal run length in pixels to classify as a scar (1–4096) |
+| max_width | INT | 4 | Maximum vertical width in pixels for a scar candidate (1–32) |
+
+## Limitations
+
+- Designed for horizontal (fast-scan) scars only; vertical scars are not detected.
+- Aggressive thresholds may remove legitimate surface features that resemble scars.