- Add Mason bin to Neovim PATH so formatters/linters are discoverable
- Add Mason ensure_installed for gofumpt, goimports, delve + stylua, black, yamlfmt
- Add Go filetype settings (tabs, tabwidth=4) in golang.lua
- Remove redundant Go keymaps — existing LSP and vim-test keymaps already cover everything
Co-Authored-By: Claude <noreply@anthropic.com>