fix(ci): restore actionlint rules and add blacksmith 16 ignore

.github/actionlint.yaml

@@ -1,6 +1,22 @@
+# actionlint configuration
+# https://github.com/rhysd/actionlint/blob/main/docs/config.md
+
+self-hosted-runner:
+  labels:
+    # Blacksmith CI runners
+    - blacksmith-8vcpu-ubuntu-2404
+    - blacksmith-8vcpu-windows-2025
+    - blacksmith-16vcpu-ubuntu-2404
+    - blacksmith-16vcpu-windows-2025
+    - blacksmith-16vcpu-ubuntu-2404-arm
+
+# Ignore patterns for known issues
 paths:
-  .github/workflows/**/*.{yml,yaml}:
+  .github/workflows/**/*.yml:
     ignore:
+      # Ignore shellcheck warnings (we run shellcheck separately)
+      - "shellcheck reported issue.+"
+      # Ignore intentional if: false for disabled jobs
+      - 'constant expression "false" in condition'
       # actionlint's built-in runner label allowlist lags Blacksmith additions.
-      # Keep runner validation enabled otherwise, but suppress this known false-positive.
       - 'label "blacksmith-16vcpu-[^"]+" is unknown\.'