Add pr-failure-scan agentic workflow

Periodic scan of recent failed PR CI runs. For each failure, searches open
issues for a known match and posts a single pointer comment on the PR.
Read-only otherwise; capped at 5 comments per run.

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

Author: kotlarmilos

.gitattributes

@@ -1,2 +1,4 @@
 # Apply LF to shell scripts automatically
 *.sh text eol=lf
+
+.github/workflows/*.lock.yml linguist-generated=true merge=ours

.github/aw/actions-lock.json

@@ -0,0 +1,9 @@
+{
+  "entries": {
+    "actions/github-script@v9.0.0": {
+      "repo": "actions/github-script",
+      "version": "v9.0.0",
+      "sha": "3a2844b7e9c422d3c10d287c895573f7108da1b3"
+    }
+  }
+}