feat: implement dynamic test generation and resolve pre-commit conflicts

- Replace static test fixture files with dynamic test generation
- Implement comprehensive test suite with unit, integration, and golden master tests
- Add vim API mocking for standalone Lua test execution
- Fix pre-commit hook interference by eliminating external fixture files
- Add StyLua formatting for consistent Lua code style
- Enhance ShellSpec formatting with improved HEREDOC and comment handling
- Update documentation with new test architecture details

This resolves issues where pre-commit hooks (shfmt, end-of-file-fixer) were
modifying test fixture files and breaking golden master tests. The new dynamic
approach generates test data programmatically, making tests immune to formatting
tools while maintaining comprehensive coverage.

lua/shellspec/autocmds.lua

@@ -10,11 +10,13 @@ local augroup = vim.api.nvim_create_augroup("ShellSpec", { clear = true })
 local function setup_buffer(bufnr)
   -- Set buffer options
   vim.api.nvim_set_option_value("commentstring", "# %s", { buf = bufnr })
-  vim.api.nvim_set_option_value("foldmethod", "indent", { buf = bufnr })
   vim.api.nvim_set_option_value("shiftwidth", config.get("indent_size"), { buf = bufnr })
   vim.api.nvim_set_option_value("tabstop", config.get("indent_size"), { buf = bufnr })
   vim.api.nvim_set_option_value("expandtab", config.get("use_spaces"), { buf = bufnr })
 
+  -- Set window-local options (foldmethod is window-local)
+  vim.api.nvim_set_option_value("foldmethod", "indent", { win = 0 })
+
   -- Buffer-local commands
   vim.api.nvim_buf_create_user_command(bufnr, "ShellSpecFormat", function()
     format.format_buffer(bufnr)
@@ -35,6 +37,18 @@ end
 
 -- Create all autocommands
 function M.setup()
+  -- Create global commands first
+  vim.api.nvim_create_user_command("ShellSpecFormat", function()
+    format.format_buffer()
+  end, { desc = "Format current ShellSpec buffer" })
+
+  vim.api.nvim_create_user_command("ShellSpecFormatRange", function(cmd_opts)
+    format.format_selection(0, cmd_opts.line1, cmd_opts.line2)
+  end, {
+    range = true,
+    desc = "Format ShellSpec selection",
+  })
+
   -- FileType detection and setup
   vim.api.nvim_create_autocmd("FileType", {
     group = augroup,