Add weekly resource staleness report agentic workflow

Scans agents, prompts, instructions, hooks, and skills folders to
identify resources that haven't had a major change in over 30 days
(stale) or 14 days (aging). Runs weekly or on demand and files a
GitHub issue with the report.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/aw/actions-lock.json

@@ -0,0 +1,14 @@
+{
+  "entries": {
+    "actions/github-script@v8": {
+      "repo": "actions/github-script",
+      "version": "v8",
+      "sha": "ed597411d8f924073f98dfc5c65a23a2325f34cd"
+    },
+    "github/gh-aw/actions/setup@v0.45.7": {
+      "repo": "github/gh-aw/actions/setup",
+      "version": "v0.45.7",
+      "sha": "5d8900eb6f6230c9d41a3c30af320150a2361285"
+    }
+  }
+}