added shfmt for shell scripts

Format sh/bash files with shfmt via conform and install it through
mason-tool-installer.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -29,7 +29,7 @@ Personal Neovim configuration using [lazy.nvim](https://github.com/folke/lazy.nv
 
 - `mason.nvim` — installs LSP servers and tools
 - `mason-lspconfig.nvim` — bridges Mason with nvim-lspconfig; auto-installs: `html`, `cssls`, `lua_ls`, `pyright`
-- `mason-tool-installer.nvim` — installs formatters/linters: `prettier`, `stylua`, `isort`, `black`, `pylint`
+- `mason-tool-installer.nvim` — installs formatters/linters: `prettier`, `stylua`, `isort`, `black`, `pylint`, `shfmt`
 - `blink.cmp` (`lua/holger/plugins/blink-cmp.lua`) — sets up LSP capabilities via `vim.lsp.config("*", ...)` (native Neovim LSP API)
 - `lazydev.nvim` — Lua LSP annotations for Neovim API (`vim.*`)
 
@@ -46,6 +46,7 @@ Personal Neovim configuration using [lazy.nvim](https://github.com/folke/lazy.nv
   - CSS/HTML/JSON/YAML/Markdown/GraphQL → prettier
   - Lua → stylua
   - Python → isort + black
+  - Shell (sh/bash) → shfmt
 - **nvim-lint** — lints on BufEnter/BufWritePost/InsertLeave; `<leader>l` to trigger manually
   - Python → pylint