feat(ci): use gh-pages for baseline, add permissions, apply review feedback

- Switch PR comparison from actions/cache to gh-pages branch
- Add permissions (contents: write, pull-requests: write) for
  alert comments and gh-pages auto-push
- Lower alert threshold to 110%
- Restrict to github.repository == 'kube-rs/kube'

Signed-off-by: doxxx <doxxx93@gmail.com>

Author: doxxx93

.github/workflows/memory-bench.yml

@@ -21,9 +21,14 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
+permissions:
+  contents: write
+  pull-requests: write
+
 jobs:
   memory-bench:
     runs-on: ubuntu-latest
+    if: github.repository == 'kube-rs/kube'
     steps:
       - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
@@ -32,19 +37,27 @@ jobs:
       - name: Run memory benchmark
         run: cargo bench -p kube-runtime --bench memory > bench-result.json
 
-      - name: Restore benchmark baseline
-        uses: actions/cache@v4
-        with:
-          path: ./bench-data
-          key: memory-bench-data
-
-      - name: Compare benchmarks
+      - name: Compare benchmarks (PR)
+        if: github.event_name == 'pull_request'
         uses: benchmark-action/github-action-benchmark@v1
         with:
           tool: customSmallerIsBetter
           output-file-path: bench-result.json
-          external-data-json-path: ./bench-data/data.json
           github-token: ${{ secrets.GITHUB_TOKEN }}
+          gh-pages-branch: gh-pages
+          benchmark-data-dir-path: bench
+          auto-push: false
           comment-on-alert: true
-          alert-threshold: "150%"
+          alert-threshold: "110%"
           fail-on-alert: true
+
+      - name: Store benchmark result (main)
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        uses: benchmark-action/github-action-benchmark@v1
+        with:
+          tool: customSmallerIsBetter
+          output-file-path: bench-result.json
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          auto-push: true
+          gh-pages-branch: gh-pages
+          benchmark-data-dir-path: bench