[max-models]

• Method cards (methodcard) on the numerics: the linear and quadratic shape functions (linear_cell, quadratic_cell), the deposit and the gather (Weighting.scatter_block, Weighting.gather_block) and their adjointness (Weighting), the block grid and the halo exchanges, the gradient, the smoothing filters, the prescribed field and the evaluation, with assumptions and references.
• test_method_cards.py checks them: 19 SymPy rules (shape functions, partition of unity, first moment, edge folds and periodic seams, run through the compiled kernels; the 2D linear deposit, the 3D quadratic gather, the gradient, the filters, the seam of evaluate, axial_potential), the second order of both gathers, Field.gradient and electric_field_from_potential, and the docs cards against the runtime ones.
• A Numerics section in the docs: a hand-written overview (numerics/index.mdx) and one page per module; starlight-theme 0.7.4; smoke paths for the new pages.
• Docstrings: code spans instead of :class:/:meth:/:func: roles, so they render on the API pages.
• Adds the methodcard dependency (methodcard[symbolic] in the test extra).