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/renode.sh

@@ -0,0 +1,104 @@
+#!/bin/bash
+# Step 10: Renode emulator for Arduino simulation with USB HID support
+
+step "10/12 — Installing Renode emulator"
+
+# gdb-multiarch is needed for nvim-dap to connect to Renode's GDB server
+if $IS_ARCH; then
+  if ! command -v renode &>/dev/null; then
+    info "Installing Renode from AUR..."
+    yay -S --needed --noconfirm renode-bin
+  else
+    info "Renode already installed"
+  fi
+  $PKG_INSTALL arm-none-eabi-gdb
+else
+  if ! command -v renode &>/dev/null; then
+    info "Installing Renode..."
+    RENODE_VERSION=$(curl -ks "https://api.github.com/repos/renode/renode/releases/latest" | jq -r '.tag_name' | sed 's/^v//')
+    curl -ksSLo /tmp/renode.deb "https://github.com/renode/renode/releases/download/v${RENODE_VERSION}/renode_${RENODE_VERSION}_amd64.deb"
+    sudo apt install -y /tmp/renode.deb
+    rm -f /tmp/renode.deb
+  else
+    info "Renode already installed"
+  fi
+  $PKG_INSTALL gdb-multiarch
+fi
+info "Renode installed: $(renode --version 2>/dev/null | head -1 || echo 'OK')"
+
+# ── Renode helper script ─────────────────────────────────────────
+# Provides a quick way to launch Renode with a GDB server for a firmware ELF
+cat >~/.local/bin/arduino-sim <<'SIMSCRIPT'
+#!/bin/bash
+set -euo pipefail
+
+usage() {
+  echo "Usage: arduino-sim <firmware.elf> [platform]"
+  echo ""
+  echo "Launch Renode with a GDB server for debugging firmware."
+  echo "Connect nvim-dap or gdb to localhost:3333"
+  echo ""
+  echo "Platforms:"
+  echo "  stm32f4    STM32F4 Discovery  (default)"
+  echo "  rp2040     Raspberry Pi Pico"
+  echo "  nrf52840   nRF52840 (USB HID capable)"
+  echo ""
+  echo "Example:"
+  echo "  arduino-sim build/firmware.elf nrf52840"
+  exit 1
+}
+
+[[ $# -lt 1 ]] && usage
+
+ELF="$1"
+PLATFORM="${2:-stm32f4}"
+
+[[ ! -f "$ELF" ]] && echo "Error: $ELF not found" && exit 1
+
+# Map platform to Renode machine definition
+case "$PLATFORM" in
+  stm32f4)
+    RENODE_PLATFORM="platforms/boards/stm32f4_discovery.repl"
+    MACHINE="STM32F4_Discovery"
+    ;;
+  rp2040)
+    RENODE_PLATFORM="platforms/cpus/rp2040.repl"
+    MACHINE="RP2040"
+    ;;
+  nrf52840)
+    RENODE_PLATFORM="platforms/cpus/nrf52840.repl"
+    MACHINE="nRF52840"
+    ;;
+  *)
+    echo "Unknown platform: $PLATFORM"
+    usage
+    ;;
+esac
+
+# Generate a temporary Renode script
+RESC=$(mktemp /tmp/renode-XXXXXX.resc)
+cat >"$RESC" <<EOF
+using sysbus
+
+mach create "$MACHINE"
+machine LoadPlatformDescription @$RENODE_PLATFORM
+
+sysbus LoadELF @$(realpath "$ELF")
+
+machine StartGdbServer 3333
+
+showAnalyzer sysbus.uart0 Antmicro.Renode.Analyzers.LoggingUartAnalyzer
+
+start
+EOF
+
+echo "Starting Renode ($MACHINE) with GDB server on :3333"
+echo "Connect debugger:  nvim → <leader>ds  or  gdb → target remote :3333"
+echo ""
+
+renode --disable-xwt "$RESC"
+rm -f "$RESC"
+SIMSCRIPT
+chmod +x ~/.local/bin/arduino-sim
+
+info "Renode simulation helper created (arduino-sim)"