feat: add bootstrap module and update docs

- Add lua/bootstrap.lua: redirects Neovim data/state paths when running
  as root (e.g. via symlinked ~/.config/nvim) to prevent root sessions
  from conflicting with the user-level install
- Update init.lua to require("bootstrap") before any other module
- Standardize license headers across all Lua files (capitalize author,
  add SPDX-License-Identifier)
- Update README with full plugin stack section, bootstrap docs,
  machine-local override docs, qalculate dependency, and blink.cmp
  auto-rebuild note

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lua/bootstrap.lua

@@ -0,0 +1,20 @@
+--          ╭─────────────────────────────────────────────────────────╮
+--          │                        Bootstaps                        │
+--          ╰─────────────────────────────────────────────────────────╯
+
+---- Copyright (C) 2026 Rootiest
+-- SPDX-License-Identifier: GPL-3.0-or-later
+
+-- This file is sourced before anything else so it can be used to set up
+-- the runtime path and other fundamental settings.
+
+--  ─────────────── Manage root user permissions for Neovim ───────────────
+
+-- Redirect data directories if running as root to avoid permission issues
+if os.getenv("USER") == "root" or os.getenv("SUDO_USER") ~= nil then
+	local root_data = "/root/.local/share/nvim-root"
+	vim.opt.packpath:prepend(root_data .. "/site")
+	vim.opt.runtimepath:prepend(root_data .. "/site")
+	-- Prevent root from writing shada to your user home
+	vim.opt.shadafile = "/root/.local/state/nvim-root.shada"
+end