feat: add first-class Neovim support with enhanced formatting

- Add modern Lua implementation with modular architecture
- Implement HEREDOC preservation and smart comment indentation
- Create dual implementation (Neovim Lua + VimScript fallback)
- Add comprehensive health check and configuration system
- Enhance formatting engine with state machine for context awareness
- Update documentation with Lua configuration examples
- Add memory files for development workflow and conventions

plugin/shellspec.vim

@@ -8,22 +8,37 @@ if exists('g:loaded_shellspec')
 endif
 let g:loaded_shellspec = 1
 
-" Commands
-command! ShellSpecFormat call shellspec#format_buffer()
-command! -range ShellSpecFormatRange call shellspec#format_selection()
+" Detect Neovim and use appropriate implementation
+if has('nvim-0.7')
+  " Use modern Neovim Lua implementation
+  lua require('shellspec.autocmds').setup()
 
-" Auto commands
-augroup ShellSpec
-  autocmd!
-  autocmd FileType shellspec setlocal commentstring=#\ %s
-  autocmd FileType shellspec setlocal foldmethod=indent
-  autocmd FileType shellspec setlocal shiftwidth=2 tabstop=2 expandtab
-augroup END
+  " Create commands that delegate to Lua
+  command! ShellSpecFormat lua require('shellspec').format_buffer()
+  command! -range ShellSpecFormatRange lua require('shellspec').format_selection(0, <line1>, <line2>)
 
-" Optional: Auto-format on save
-if get(g:, 'shellspec_auto_format', 0)
-  augroup ShellSpecAutoFormat
+  " Optional: Auto-format on save (handled in Lua)
+  " This is now managed by the Lua autocmds module based on configuration
+
+else
+  " Fallback to VimScript implementation for older Vim
+  " Commands
+  command! ShellSpecFormat call shellspec#format_buffer()
+  command! -range ShellSpecFormatRange call shellspec#format_selection()
+
+  " Auto commands
+  augroup ShellSpec
     autocmd!
-    autocmd BufWritePre *.spec.sh,*_spec.sh ShellSpecFormat
+    autocmd FileType shellspec setlocal commentstring=#\ %s
+    autocmd FileType shellspec setlocal foldmethod=indent
+    autocmd FileType shellspec setlocal shiftwidth=2 tabstop=2 expandtab
   augroup END
+
+  " Optional: Auto-format on save
+  if get(g:, 'shellspec_auto_format', 0)
+    augroup ShellSpecAutoFormat
+      autocmd!
+      autocmd BufWritePre *.spec.sh,*_spec.sh ShellSpecFormat
+    augroup END
+  endif
 endif