fix: stop dependabot from proposing wrong-direction @types/node major bumps

Add an ignore rule for version-update:semver-major on @types/node to
prevent Dependabot from proposing bumps that exceed the CI/synth Node
major (24). This is a sanctioned exception — minor and patch updates
within the current major still flow normally.

Refs #16

.github/dependabot.yml

@@ -9,6 +9,14 @@ updates:
         update-types:
           - "minor"
           - "patch"
+    ignore:
+      # @types/node must track the runtime Node major, not the latest release.
+      # Pure-CDK repo: the runtime is the Node that runs `cdk synth`/`tsc` in CI.
+      # Dependabot can't see that and a too-new types major still compiles (passes
+      # CI, wrong at runtime). Sanctioned exception to the no-blanket-ignore rule
+      # (engineering-handbook github-standards Pinning Principle). Minor/patch flow.
+      - dependency-name: "@types/node"
+        update-types: ["version-update:semver-major"]
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule: