Add sample proof bundle configurations and verification script

- Introduced sample proof bundle configuration files for testing, including `sample-proof-bundle-config.dsse.json`, `sample-proof-bundle.dsse.json`, and `sample-proof-bundle.json`.
- Implemented a verification script `test_verify_sample.sh` to validate proof bundles against specified schemas and catalogs.
- Updated existing proof bundle configurations with new metadata, including versioning, created timestamps, and justification details.
- Enhanced evidence entries with expiration dates and hashes for better integrity checks.
- Ensured all new configurations adhere to the defined schema for consistency and reliability in testing.

.gitea/workflows/vex-proof-bundles.yml

@@ -0,0 +1,38 @@
+name: VEX Proof Bundles
+
+on:
+  pull_request:
+    paths:
+      - 'scripts/vex/**'
+      - 'tests/Vex/ProofBundles/**'
+      - 'docs/benchmarks/vex-evidence-playbook*'
+      - '.gitea/workflows/vex-proof-bundles.yml'
+  push:
+    branches: [ main ]
+    paths:
+      - 'scripts/vex/**'
+      - 'tests/Vex/ProofBundles/**'
+      - 'docs/benchmarks/vex-evidence-playbook*'
+      - '.gitea/workflows/vex-proof-bundles.yml'
+
+jobs:
+  verify-bundles:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+
+      - name: Install deps
+        run: pip install --disable-pip-version-check --no-cache-dir -r scripts/vex/requirements.txt
+
+      - name: Verify proof bundles (offline)
+        env:
+          PYTHONHASHSEED: "0"
+        run: |
+          chmod +x tests/Vex/ProofBundles/test_verify_sample.sh
+          tests/Vex/ProofBundles/test_verify_sample.sh