ci: add GitHub Action to validate commit message style

This workflow checks all commits between the current branch and
upstream/master. It enforces subject length, colon usage in the
subject line, and body line length. This helps maintain consistency
and readability in the project's history.

Author: szymon-czapracki

.github/workflows/compliance_check.yml

@@ -106,3 +106,70 @@ jobs:
         shell: bash
         run: |
              .github/check_doxygen.py
+
+commits-check:
+  name: Check commit messages
+  runs-on: ubuntu-latest
+  steps:
+    - uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+
+    - name: Validate commit message style
+      shell: bash
+      run: |
+        set -e
+        has_errors=0
+
+        # Determine commit range for PR or fallback to origin/master
+        if [ -n "${GITHUB_BASE_REF}" ]; then
+          base_ref="origin/${GITHUB_BASE_REF}"
+        else
+          base_ref="origin/master"
+        fi
+
+        base_commit=$(git merge-base HEAD ${base_ref})
+
+        echo "Checking commits from ${base_commit} to HEAD"
+
+        for commit in $(git rev-list ${base_commit}..HEAD); do
+          short_sha=$(git rev-parse --short=7 $commit)
+          subject=$(git log -1 --pretty=format:%s $commit)
+          body=$(git log -1 --pretty=format:%b $commit)
+
+          if [ ${#subject} -gt 72 ]; then
+            echo "Commit $short_sha subject too long (${#subject} > 72):"
+            echo "$subject"
+            has_errors=1
+          fi
+
+          if [[ "$subject" != *:* ]]; then
+            echo "Commit $short_sha subject missing colon (e.g. 'subsystem: msg')"
+            echo "$subject"
+            has_errors=1
+          fi
+
+          if [ -z "$body" ]; then
+            echo "Commit $short_sha body is missing"
+            has_errors=1
+          else
+            line_num=0
+            while IFS= read -r line; do
+              line_num=$((line_num + 1))
+              if [ ${#line} -gt 72 ]; then
+                echo "Commit $short_sha body line $line_num too long (${#line} > 72):"
+                echo "$line"
+                has_errors=1
+              fi
+            done <<< "$body"
+          fi
+
+          echo ""
+        done
+
+        if [ "$has_errors" -eq 1 ]; then
+          echo "Commit message check failed."
+          exit 1
+        else
+          echo "All commit messages pass style rules."
+        fi