feat: autograd support for Clip Operations

[rahul-flex]

Autograd support for ClipOperation with respect to the vertices and slab_bounds of its constituent PolySlab.

Key Changes:
Differentiable Geometry Representation:
Introduces a "soft membership" function. It provides a smooth, differentiable approximation of the sharp boundaries and non-differentiable nature of boolean geometric operations (intersection, union, difference and symmetric-difference), enabling gradient computation.

Adjoint-Based Derivative Calculation:
Computes gradients using the adjoint method, integrating permittivity sensitivity , and the gradient of the soft membership function wrt polylab params.

Expanded Monitor Bounds:
Adjoint monitors now encompass both input geometries with padding, ensuring accurate field capture for derivative calculations near boundaries.

Validation:
Results verified against finite-difference checks for all parameters and boolean operation types (attached).

[notion-workspace]

✂️ ClipOperation support