feat: add validation tooling and expand path review instructions

Add pre-commit hooks (YAML lint, schema validation, editorconfig),
CI workflow, and new path instructions for test files, Dockerfiles,
config files, and archival docs.

.github/workflows/validate.yml

@@ -0,0 +1,21 @@
+---
+name: Validate Configuration
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+      - uses: pre-commit/action@v3.0.1