ci: 👷 add GitHub Actions workflows

Author: tomgrv

.github/copilot.yaml

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+# @format
+
+instructions:
+    pull_request:
+        title:
+            description: >
+                Titles for pull requests must follow Conventional Commit rules. Start with a type (e.g., feat, fix, docs, style, refactor, perf, test, chore) followed by a colon and a brief summary. Optionally, add a scope in parentheses. Example: "feat(parser): add support for new syntax".
+            examples:
+                - 'feat(login): add OAuth2 support'
+                - 'fix(api): correct null pointer error in user endpoint'
+                - 'docs(readme): update installation instructions'
+                - 'refactor(auth): streamline token validation logic'
+                - 'chore(deps): bump version of express to 4.18.2'
+            must_match_regex: '^(feat|fix|docs|style|refactor|perf|test|chore)(\([a-z0-9\-]+\))?:\s.+'
+            error_message: >
+                Pull request titles must follow Conventional Commit rules (e.g., "feat(login): add OAuth2 support"). Please update your PR title.

.github/workflow/rebase-pr.yml

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+# @format
+
+name: Automatic Rebase
+on:
+  issue_comment:
+    types: [created]
+jobs:
+  rebase:
+    name: Rebase
+    runs-on: ubuntu-latest
+    if: >-
+      github.event.issue.pull_request != '' && 
+      (
+        contains(github.event.comment.body, '/rebase') || 
+        contains(github.event.comment.body, '/autosquash')
+      )
+    steps:
+      - name: Checkout the latest code
+        uses: actions/checkout@v3
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          fetch-depth: 0 # otherwise, you will fail to push refs to dest repo
+      - name: Automatic Rebase
+        uses: cirrus-actions/rebase@1.8
+        with:
+          autosquash: ${{ contains(github.event.comment.body, '/autosquash') || contains(github.event.comment.body, '/rebase-autosquash') }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}