🐛 fix(placement): correct debug permission checks and reject bad methods (#1623)

Map GET/POST debug requests to get/create SAR verbs and return 403 on
denial. Reject unsupported HTTP methods with 405 instead of treating
them as GET. Update the GET RBAC integration test Role to grant get.

Also free unused disk on e2e runners before image builds to reduce
"no space left on device" flakes.

Fixes open-cluster-management-io/ocm#1622

Signed-off-by: Roke Jung <roke@redhat.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

.github/scripts/free-disk-space.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Reclaim disk on GitHub-hosted Ubuntu runners before heavy image builds.
+set -euo pipefail
+
+echo "::group::Disk before"
+df -h /
+echo "::endgroup::"
+
+sudo rm -rf \
+  /usr/share/dotnet \
+  /usr/local/lib/android \
+  /opt/ghc \
+  /opt/hostedtoolcache/CodeQL \
+  /usr/local/share/boost \
+  /usr/share/swift \
+  /usr/local/.ghcup || true
+
+sudo docker image prune -af || true
+sudo docker builder prune -af || true
+
+echo "::group::Disk after"
+df -h /
+echo "::endgroup::"