fix: minerva sympy memory limit

[prabhuteja12]

PR Checklist

• Use descriptive commit messages.
• Provide tests for your changes.
• Update any related documentation and include any relevant screenshots.
• Check if changes need to be made to docs (README or any guides in /docs/).

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

Replace the one-process-per-call architecture in is_equiv_minerva with a persistent subprocess that handles many equivalence checks over its lifetime, plus an LRU cache to short-circuit repeated pairs entirely.

Related Tickets & Documents

• Related Issue #
• Closes #

QA Instructions, Screenshots, Recordings

Please replace this line with instructions on how to test your changes, a note
on the hardware and config this has been tested on, as well as any relevant
additional information.

Added/updated tests?

• Yes
• No, and this is why: please replace this line with details on why tests
  have not been included
• I need help with writing tests

[optional] Are there any post deployment tasks we need to perform?