chore: refactoring

[leodemoura]

This PR refactors the grind and Sym modules using Claude-assisted code transformations as an experiment in AI-aided code maintenance.

Remark: do not merge

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 03ffde3fde4a3c8c45b1f431e8711f5f250e808a --onto 4cdc199f772977113bd6c1bf87a6c02b78d5c4d3. You can force Mathlib CI using the force-mathlib-ci label. (2026-02-12 02:37:20)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 03ffde3fde4a3c8c45b1f431e8711f5f250e808a --onto 03dc334f73259e1bae0b8f2b80a39a82e1de3df6. You can force reference manual CI using the force-manual-ci label. (2026-02-12 02:37:22)