Add CI, dirval-based validator, tests, and docs updates

• Add GitHub Actions workflow (Ubuntu, Python 3.10–3.12)
• Add Makefile (test + pkgmgr install note)
• Add requirements.yml (pkgmgr: dirval)
• Replace shell scripts with parallel validator main.py using dirval
• Add unit tests with fake dirval and timeouts
• Update README to new repo name and pkgmgr alias 'cleanback'
• Add .gitignore for __pycache__

Conversation context: https://chatgpt.com/share/68c309bf-8818-800f-84d9-c4aa74a4544c

.github/workflows/tests.yml

@@ -0,0 +1,41 @@
+name: CI
+
+on:
+  push:
+    branches: [ "**" ]
+  pull_request:
+    branches: [ "**" ]
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+        python-version: ["3.10", "3.11", "3.12"]
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Show Python version
+        run: python -V
+
+      - name: Make main.py executable (optional)
+        run: chmod +x main.py || true
+
+      - name: Install test dependencies (if any)
+        run: |
+          if [ -f requirements.txt ]; then
+            python -m pip install --upgrade pip
+            pip install -r requirements.txt
+          fi
+
+      - name: Run tests
+        run: make test