ci: add the org Semgrep workflow, CODEOWNERS and Dependabot config

.github/CODEOWNERS

@@ -0,0 +1,3 @@
+/.github/workflows/required-checks.yml @PrunaAI/safety
+/.github/scripts/check_run_secrets.py @PrunaAI/safety
+/.github/CODEOWNERS @PrunaAI/safety

.github/dependabot.yml

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+version: 2
+updates:
+  - package-ecosystem: github-actions
+    cooldown:
+      default-days: 7
+    directories:
+      - "/"
+    schedule:
+      interval: weekly
+    groups:
+      minor-and-patch:
+        patterns: ["*"]
+        update-types: [minor, patch]
+  - package-ecosystem: docker
+    directories:
+      - "/.github/workflows"
+    schedule:
+      interval: weekly
+    cooldown:
+      default-days: 7

.github/scripts/check_run_secrets.py

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+#!/usr/bin/env python3
+"""Fail if a workflow `run:` step interpolates `${{ secrets.* }}` directly into the shell.
+
+Interpolating a secret into a run script leaks it via shell history, process listings
+and command echoing, and opens script injection. Pass it through `env:` and reference
+the environment variable inside the script instead (see PrunaAI/prunatree#641).
+"""
+import pathlib
+import re
+import sys
+
+import yaml
+
+SECRET_PATTERN = re.compile(r"\$\{\{\s*secrets\.")
+
+
+def iter_run_steps(workflow: dict):
+    for job in (workflow.get("jobs") or {}).values():
+        if not isinstance(job, dict):
+            continue
+        for step in job.get("steps") or []:
+            run = step.get("run") if isinstance(step, dict) else None
+            if isinstance(run, str):
+                yield step.get("name", "<unnamed step>"), run
+
+
+def main() -> int:
+    violations = []
+    for path in sorted(pathlib.Path(".github/workflows").glob("*.y*ml")):
+        workflow = yaml.safe_load(path.read_text())
+        if not isinstance(workflow, dict):
+            continue
+        for name, run in iter_run_steps(workflow):
+            if SECRET_PATTERN.search(run):
+                violations.append(
+                    f"{path}: step {name!r} interpolates a secret directly into `run:` "
+                    "— pass it through `env:` and reference the env var instead"
+                )
+
+    if violations:
+        print("\n".join(violations))
+        return 1
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

.github/workflows/required-checks.yml

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+name: required checks
+
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  required-checks:
+    runs-on: ubuntu-latest
+    container:
+      image: semgrep/semgrep:1.178.0@sha256:32e459968daabe7ab86968184a29109b9564aa00392401156f9788452b42786b
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+        with:
+          fetch-depth: 0
+      - name: Semgrep (only findings this pull request adds)
+        run: |
+          git config --global --add safe.directory "$GITHUB_WORKSPACE"
+          semgrep scan --config p/trailofbits --config p/default --severity ERROR --error --metrics off \
+            --baseline-commit "${{ github.event.pull_request.base.sha }}"
+      - name: No secrets interpolated directly into run steps
+        run: |
+          apk add --no-cache py3-yaml
+          python3 .github/scripts/check_run_secrets.py