Refactor: modernize plugin, deduplicate code, improve robustness

[sigfriedCub1990]

Summary

Comprehensive refactoring of the nvim-pytrize.lua codebase addressing code duplication, API modernization, performance, and robustness. All 77 tests pass.

Commits (4 steps)

1. Critical fixes (5a6078c)

• Extract shared helpers — Duplicated get_param_name_node, find_body_references, and find_fixture_references from rename.lua and usages.lua into new lua/pytrize/ts_helpers.lua. Reduces usages.lua by ~70% and rename.lua by ~40%.
• Modernize commands — Replace vim.cmd('command ... lua ...') with vim.api.nvim_create_user_command() with desc fields.
• Error handling — Add pcall to treesitter parser in call_spec.lua; add file/JSON error handling in nodeids.lua.
• Fragile tree access — Replace arguments:child(N) with named children iteration in call_spec.lua.

2. API modernization (b7bee1d)

• Simplify marks.lua — Replace manual extmark ID tracking with nvim_buf_clear_namespace().
• Simplify warn.lua — Remove vestigial vim.fn.escape() and \n handling; just call vim.notify().
• Remove custom min/max — Use math.min/math.max directly.
• Modernize utils.with_buf — Use nvim_buf_is_loaded(), vim.bo[], vim.fn.bufload(), pcall safety.
• Modernize jump/util.lua — Use vim.cmd.edit().

3. Performance & robustness (0df39da)

• Cache treesitter query — Parse parametrize query once at module level in call_spec.lua.
• Settings type validation — Reject values with wrong type in settings.update().
• Cache auto-invalidation — Add BufWritePost/BufDelete autocommand to clear stale fixture scan cache entries.

4. Polish (f75d777)

• Health check — Add lua/pytrize/health.lua for :checkhealth pytrize.
• LuaCATS annotations — Add @param/@return/@class to key modules.
• Drop compat shim — Use vim.treesitter.query.parse directly (requires Neovim >= 0.9).

Files changed

File	Action
lua/pytrize/ts_helpers.lua	New — shared treesitter helpers
lua/pytrize/health.lua	New — :checkhealth support
lua/pytrize/rename.lua	Rewritten to use shared helpers
lua/pytrize/usages.lua	Rewritten to use shared helpers
lua/pytrize/marks.lua	Simplified extmark management
lua/pytrize/warn.lua	Simplified
lua/pytrize/utils.lua	Removed min/max, modernized with_buf
lua/pytrize/call_spec.lua	Error handling, query caching, robust access
lua/pytrize/nodeids.lua	Error handling
lua/pytrize/init.lua	Modern commands, annotations
lua/pytrize/api.lua	Annotations, idiomatic patterns
lua/pytrize/ts.lua	Cache auto-invalidation
lua/pytrize/settings.lua	Type validation, annotations
lua/pytrize/jump/util.lua	Modernized
lua/pytrize/jump/param.lua	Uses math.min/max
tests/pytrize/utils_spec.lua	Updated for new API
tests/pytrize/usages_spec.lua	Updated export name
tests/pytrize/settings_spec.lua	Added type validation test