ci: add Dependabot (GitHub Actions) and a stale issue/PR bot

- dependabot.yml: monthly grouped updates for the github-actions
  ecosystem, with a 7-day cooldown.
- stale.yml: close inactive issues and PRs, scoped to specific status
  labels rather than all activity.

Signed-off-by: Pouyanpi <13303554+Pouyanpi@users.noreply.github.com>

Author: Pouyanpi

.github/dependabot.yml

@@ -0,0 +1,12 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: monthly
+    cooldown:
+      default-days: 7
+    groups:
+      github-actions:
+        patterns:
+          - "*"

.github/workflows/stale.yml

@@ -0,0 +1,31 @@
+name: Close stale issues and PRs
+
+on:
+  schedule:
+    - cron: "0 14 * * *"
+  workflow_dispatch:
+
+permissions: {}
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+      - uses: actions/stale@v9
+        with:
+          any-of-issue-labels: "status: needs info,status: waiting confirmation"
+          days-before-issue-stale: 14
+          days-before-issue-close: 7
+          stale-issue-label: "status: stale"
+          stale-issue-message: "This issue is stale because it has been open with no activity. It will be closed in 7 days if no further activity occurs."
+          close-issue-message: "Closing this issue as it has been inactive. Please reopen if it is still relevant."
+
+          any-of-pr-labels: "status: needs info"
+          days-before-pr-stale: 21
+          days-before-pr-close: 7
+          stale-pr-label: "status: stale"
+          stale-pr-message: "This PR is stale because it has been open with no activity. It will be closed in 7 days if no further activity occurs."
+          close-pr-message: "Closing this PR as it has been inactive. Please reopen if you intend to continue."