Add workflow to automatically update LICENSE year

Author: nghtctrl

.github/workflows/update-license-year.yml

@@ -0,0 +1,50 @@
+name: Update LICENSE year
+
+on:
+  schedule:
+    # Runs at 00:10 UTC every Jan 1
+    - cron: '10 0 1 1 *'
+  workflow_dispatch: {}
+
+permissions:
+  contents: write
+
+jobs:
+  update-year:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repo
+        uses: actions/checkout@v4
+
+      - name: Update year in LICENSE.md (MIT header line)
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          FILE="LICENSE.md"
+          YEAR="$(date -u +%Y)"
+
+          if [[ ! -f "$FILE" ]]; then
+            echo "ERROR: $FILE not found."
+            exit 1
+          fi
+
+          # Replace ONLY the 4-digit year after "Copyright (c)"
+          # e.g. "Copyright (c) 2026 Jiho Kim" -> "Copyright (c) 2027 Jiho Kim"
+          perl -0777 -i -pe "s/(Copyright\\s*\\(c\\)\\s*)\\d{4}(\\s+)/\$1$YEAR\$2/g" "$FILE"
+
+          if git diff --quiet; then
+            echo "No changes needed."
+            exit 0
+          fi
+
+      - name: Commit and push if changed
+        shell: bash
+        run: |
+          set -euo pipefail
+          git config user.name  "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+          git add LICENSE.md
+          git commit -m "Update LICENSE year to $(date -u +%Y)"
+          git push