Add a codespell spellcheck pass to the lint job

Author: aidangarske

.github/scripts/lint.sh

@@ -37,6 +37,13 @@ if command -v cppcheck >/dev/null 2>&1; then
         || echo "cppcheck: reported issues above (informational)"
 fi
 
+# codespell over the repo's own text. Informational: vendored SDKs and binary
+# assets are skipped, and common-word false positives should not fail the build.
+if command -v codespell >/dev/null 2>&1; then
+    codespell --skip='./.git,*/pico-sdk/*,*/mcux-sdk/*,*.der,*.pem,*.raw,*.enc' \
+        . || echo "codespell: reported issues above (informational)"
+fi
+
 # make -n parses every Makefile without building. Informational: a few dirs
 # (RT1060, riot, SGX, uefi) are driven by external SDKs whose fragments a bare
 # make cannot resolve, so a parse miss there is expected, not a defect.

.github/workflows/lint.yml

@@ -2,6 +2,7 @@ name: Lint
 
 on:
   push:
+    branches: [master]
     paths:
       - '**/*.sh'
       - '**/*.c'
@@ -35,10 +36,10 @@ jobs:
     steps:
       - uses: actions/checkout@v5
       - uses: ./.github/actions/apt-update
-      - name: Install shellcheck + cppcheck + actionlint
+      - name: Install shellcheck + cppcheck + codespell + actionlint
         run: |
           set -euo pipefail
-          sudo apt-get install -y --no-install-recommends shellcheck cppcheck
+          sudo apt-get install -y --no-install-recommends shellcheck cppcheck codespell
           .github/scripts/retry.sh bash -c \
             'bash <(curl -fsSL https://raw.githubusercontent.com/rhysd/actionlint/main/scripts/download-actionlint.bash)'
           echo "$PWD" >> "$GITHUB_PATH"