feat(cutout): implement boundary padding for cutout textures

- Introduced a new `Boundary Padding` preference in the Cutout Tool with a default of 2 px and a configurable range of 1-4 px.
- Updated the Cutout client to establish inward mapping from the final Mask, sampling in a fixed direction and processing independent material RGBA and Depth.
- Enhanced the handling of RGBA and Depth during cutout operations, ensuring proper mapping and preservation of source data.
- Added tests to validate the new boundary padding functionality and its integration with existing cutout processes.

feat(geometry): remove overall mesh smoothing from geometry nodes

- Removed the `Smooth` input from several geometry node groups to eliminate unnecessary overall mesh smoothing.
- Retained `Smooth Weight` for depth nodes while removing it from Cutout and Relief Plane nodes.
- Ensured that boundary, normal, and fill smoothing behaviors remain intact and consistent.
- Updated tests and documentation to reflect the changes in node interfaces and behaviors.

feat(normals): scale tangent normals with depth

- Reused the existing `o_normal_reduction` attribute to adjust Tangent Normal strength based on the geometry's `Depth Scale`.
- Ensured that Tangent Normal strength is consistent with the geometry depth, preserving full strength for materials that do not provide the attribute.
- Updated tests to verify the correct behavior of normal strength adjustments in both Tangent and Object Space.

openspec/changes/scale-tangent-normals-with-depth/proposal.md

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+## Why
+
+Tangent-space normal maps describe the full-depth surface.  When a geometry node reduces its `Depth Scale`, its shape becomes flatter but the material normal remains at full strength, making surface detail appear too strong.
+
+## What Changes
+
+- Reuse the existing `o_normal_reduction` geometry attribute as the material-to-geometry contract for tangent-space normal strength.
+- Make tangent-normal depth geometry write `1 - Depth Scale` to that attribute, so the material normal strength follows the displayed geometric depth.
+- Extend the existing `O Image Layer` behavior without changing its attribute lookup or fallback semantics.
+- Make Object Space normal strength follow the same geometry reduction contract.
+- Reuse the existing `o_normal_reduction` contract for additional Tangent-normal depth geometry.
+
+## Capabilities
+
+### New Capabilities
+- `depth-scaled-tangent-normals`: Keep tangent-space material normal strength consistent with geometry depth scaling.
+
+### Modified Capabilities
+
+None.
+
+## Impact
+
+- Tangent-normal geometry-group builders, especially Relief Plane.
+- Normal-scale node tests; saved node assets must be rebuilt with `uv run node-group build`.
+- No server inference format, user-facing modifier socket, or dependency changes.