feat: Implement diff-scope functionality for pull requests and CI integration

docs/integrations/github-actions.mdx

@@ -18,6 +18,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - name: Install Strix
         run: curl -sSL https://strix.ai/install | bash
@@ -58,3 +60,7 @@ The workflow fails when vulnerabilities are found:
 <Tip>
 Use `quick` mode for PRs to keep feedback fast. Schedule `deep` scans nightly.
 </Tip>
+
+<Note>
+For pull_request workflows, Strix automatically uses changed-files diff-scope in CI/headless runs. If diff resolution fails, ensure full history is fetched (`fetch-depth: 0`) or set `--diff-base`.
+</Note>