add a few more nodes

docs/nodes/Sphere Revolve.md

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+# Sphere Revolve
+
+Subtract a spherical cap background. A sphere of the given radius is rolled under the surface, and the envelope it traces is subtracted as the background.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with spherical background subtracted |
+| background | DATA_FIELD | The estimated spherical background |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| radius | INT | 20 | Sphere radius in pixels (1–500) |
+
+## Notes
+
+- Works like Arc Revolve but in two dimensions — suitable for bowl-shaped or dome-shaped backgrounds.
+- Larger radii produce smoother backgrounds. Very small radii will track individual features.
+- Deep outliers are suppressed before fitting.