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.

.yamllint.yaml

@@ -0,0 +1,13 @@
+---
+extends: default
+rules:
+  line-length:
+    max: 120
+    allow-non-breakable-words: true
+    allow-non-breakable-inline-mappings: true
+  truthy:
+    check-keys: false
+    allowed-values: ['true', 'false', 'on', 'off']
+  comments:
+    min-spaces-from-content: 1
+  document-start: enable