migrate: stow → chezmoi

- restructure repo to chezmoi conventions (dot_ prefix, private_dot_ssh/)
- add nvim config (was untracked)
- encrypt restic pass.txt with age
- remove stow artifacts (.stow-local-ignore, stow package dirs)
- update bootstrap.sh to use chezmoi apply
- remove runtime files from tracking (micro buffers, zed backup)

dot_config/nvim/lua/config/autocmds.lua

@@ -0,0 +1,8 @@
+-- Autocmds are automatically loaded on the VeryLazy event
+-- Default autocmds that are always set: https://github.com/LazyVim/LazyVim/blob/main/lua/lazyvim/config/autocmds.lua
+--
+-- Add any additional autocmds here
+-- with `vim.api.nvim_create_autocmd`
+--
+-- Or remove existing autocmds by their group name (which is prefixed with `lazyvim_` for the defaults)
+-- e.g. vim.api.nvim_del_augroup_by_name("lazyvim_wrap_spell")