tools: add sensor node patch script

tools/apply_xiao_sensor_node_patch.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+PATCH_COMMIT="a701059"
+
+repo_root="$(git rev-parse --show-toplevel)"
+cd "$repo_root"
+
+if [[ -n "$(git status --porcelain)" ]]; then
+    echo "Refusing to edit a dirty working tree." >&2
+    exit 1
+fi
+
+if ! git cat-file -e "${PATCH_COMMIT}^{commit}" 2>/dev/null; then
+    git fetch origin
+fi
+
+if ! git merge-base --is-ancestor "$PATCH_COMMIT" HEAD; then
+    git cherry-pick "$PATCH_COMMIT"
+else
+    echo "XIAO sensor-node patch is already applied."
+fi
+
+if [[ ! -f .venv/bin/activate ]]; then
+    echo "Missing .venv/bin/activate; create the project virtual environment first." >&2
+    exit 1
+fi
+
+source .venv/bin/activate
+python run_tests.py
+
+git add -A
+if ! git diff --cached --quiet; then
+    git commit -m "firmware: apply XIAO C6 sensor node patch"
+fi
+
+branch="$(git branch --show-current)"
+if [[ -z "$branch" ]]; then
+    echo "Cannot push from detached HEAD." >&2
+    exit 1
+fi
+git push origin "$branch"