Upgrade setup-node to v6 (#2833)

* Add actions-lock.json to manage GitHub Actions dependencies

* Fix tests for setup-node v6 upgrade (#2834)

* Fix TestAgentFileValidation to use relative paths (#2836)

---------

Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>

Author: pelikhan

.github/aw/actions-lock.json

@@ -20,11 +20,6 @@
       "version": "v5",
       "sha": "d35c59abb061a4a6fb18e82ac0862c26744d6ab5"
     },
-    "actions/setup-node@v5": {
-      "repo": "actions/setup-node",
-      "version": "v5",
-      "sha": "a0853c24544627f65ddf259abe73b1d18a591444"
-    },
     "actions/setup-node@v6": {
       "repo": "actions/setup-node",
       "version": "v6",

.github/copilot/instructions/ci-performance.md

@@ -127,7 +127,7 @@ test:
 
 ### 4. Dependency Caching Improvements
 
-**Current**: Good caching via `actions/setup-go@v5` and `actions/setup-node@v5`.
+**Current**: Good caching via `actions/setup-go@v5` and `actions/setup-node@v6`.
 
 **Enhanced Caching**:
 ```yaml

.github/workflows/artifacts-summary.lock.yml

@@ -77,7 +77,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v5
       - name: Set up Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: "24"
           cache: npm