Add CI workflow for tests and enrichment dry-run

Two jobs:
- test: builds and runs cargo test
- enrichment-dry-run: runs the pipeline against 10 real advisories
  using the Actions GITHUB_TOKEN, uploads vuln_db.json as artifact

https://claude.ai/code/session_01AeNG3herWfKhos9uZVUY5d

.github/workflows/ci.yml

@@ -0,0 +1,72 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo registry & build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-
+
+      - name: Build
+        run: cargo build --verbose
+
+      - name: Run tests
+        run: cargo test --verbose
+
+  enrichment-dry-run:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo registry & build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-
+
+      - name: Build
+        run: cargo build
+
+      - name: Run enrichment pipeline (10 advisories)
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: cargo run -- --limit 10 --output vuln_db.json
+
+      - name: Show output
+        run: cat vuln_db.json
+
+      - name: Upload enriched DB artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: vuln-db
+          path: vuln_db.json