feat: add Renode emulator, nvim-dap debugging, and backup collision fix

- Add Renode installation (AUR/deb) with arduino-sim helper script
  supporting STM32F4, RP2040, and nRF52840 (USB HID) platforms
- Add nvim-dap + nvim-dap-ui with GDB remote adapter for Renode debugging
- Add debug keybindings under <leader>d prefix
- Fix backup_config() path collisions when multiple sources share a
  basename (e.g. ~/.config/nvim and ~/.local/share/nvim)
- Strip NvChad starter's nvim-lspconfig block that conflicts with
  native vim.lsp.config, preserving configs/lazy.lua
- Update step counts from 11 to 12 (TOTAL_STEPS 12→13, 13→14 on WSL)

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

lib/arduino.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 # Step 7: Arduino CLI + board cores
 
-step "9/11 — Installing Arduino CLI + board cores"
+step "9/12 — Installing Arduino CLI + board cores"
 
 if $IS_ARCH; then
   $PKG_INSTALL arduino-cli