Fix rustls-webpki Dependabot alert and add cargo audit to CI (#160)

* Drop legacy AWS KMS TLS stack and gate deps with cargo audit.

Disable aws-sdk-kms default rustls features to remove rustls-webpki 0.101.7, bump quinn for RUSTSEC-2026-0185, and run cargo audit on ubuntu-24.04-arm CI.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Fix cargo audit CI step for cargo-audit 0.22 CLI.

Run audit from greenfloor-engine/ because cargo-audit no longer accepts --manifest-path.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: hoffmang9

.github/workflows/ci.yml

@@ -206,6 +206,17 @@ jobs:
           shared-key: test
           install-nextest: "true"
 
+      - name: Install cargo-audit
+        if: matrix.os == 'ubuntu-24.04-arm'
+        uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-audit
+
+      - name: Cargo audit (greenfloor-engine)
+        if: matrix.os == 'ubuntu-24.04-arm'
+        working-directory: greenfloor-engine
+        run: cargo audit
+
       - name: Build and test greenfloor-engine
         run: cargo nextest run --manifest-path "${{ env.CARGO_MANIFEST }}" --features test-support