Refactor meshplot / LLM experiment

[ashwinvis]

Initial implementation was done in #84

The following resulted in #145.

I should have done this in another branch. The prompts used for Claude Code Sonnet 4.5 (with "thinking" mode) were:

• /init
• (plan) The current branch contains a meshplot module, to plot mesh. Recommend alternate libraries to do the same.
• (plan) I merged with main branch which introduces changes to the package. Uses src-layout and pyproject.toml. Update the current plan accordingly.
• /plan open add some manual edits.
• Implement Option B: with support for both Pyvista and Matplotlib backends. Use git commit after meaningful changes are made. NEVER use git push.
• Separate pyvista and matplotlib backends into 2 different modules. Use typing.Protocol and runtime_checkable so that the functions match.
• Move all newly created visualization modules under a subpackage pymech.viz (rate limited!)

Next steps, try to recreate this using an open source model.

[ashwinvis]

Generated plans and CLAUDE.md files:

Plan file: floating-launching-pony.md

CLAUDE.md

[ashwinvis]

I should have used /clear and /compact to avoid so much context. https://kentgigger.com/posts/claude-code-conversation-history#essential-slash-commands-while-youre-working

[ashwinvis]

Resuming the session with:

• /compact
• Continue refactoring pymech.viz subpackage.
• (manual edits on tests)
• Run test suite tests/test_pyvista.py and fix