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.

tests/Vex/ProofBundles/cas/graph.json

@@ -0,0 +1,18 @@
+{
+  "graph_version": "richgraph-v1",
+  "root": "pkg:demo/app@1.0.0",
+  "nodes": 3,
+  "edges": 2,
+  "hashing": "blake3-256",
+  "generated_at": "2025-12-03T23:45:00Z",
+  "paths": [
+    {
+      "from": "pkg:demo/app@1.0.0#main",
+      "to": "pkg:demo/lib@1.0.0#render"
+    },
+    {
+      "from": "pkg:demo/lib@1.0.0#render",
+      "to": "pkg:demo/lib@1.0.0#helper"
+    }
+  ]
+}