fix: use valid lualine catppuccin theme

[dmoliveira]

Summary

• switch the repo-managed lualine theme from catppuccin to catppuccin-nvim
• match the current theme module exposed by the installed catppuccin integration
• remove the startup warning shown when opening Neovim locally

Validation

• make pre-commit-run
• lua -e "assert(loadfile('run_commands/my_nvim_init.lua'))"
• nvim --headless -u run_commands/my_nvim_init.lua +qa
• require("lualine.themes.catppuccin-nvim") succeeds