feat(registry): add AES-CTR-HMAC-SHA1-96 suite pattern (RFC 3686) (#771)

As discussed in ticket #770, this PR proposes adding an AES-CTR +
HMAC-SHA1-96 (IPsec ESP suite-style) pattern to the Cryptography
Registry.

Fixes #770

Details
- Adds pattern `AES[-(128|192|256)]-CTR-HMAC-SHA1[-96]` under the
existing `AES` family.
- Adds RFC 3686 as the authoritative reference.
- Registry-only change (`schema/cryptography-defs.json`). No schema or
specification behavior changes.

Author: stevespringett

schema/cryptography-defs.json

@@ -338,6 +338,16 @@
           "pattern": "AES[-(128|192|256)][-(GCM|CCM)][-{tagLength}][-{ivLength}]",
           "primitive": "ae"
         },
+        {
+          "standard": [
+            {
+              "name": "RFC 3686",
+              "url": "https://doi.org/10.17487/RFC3686"
+            }
+          ],
+          "pattern": "AES[-(128|192|256)]-CTR-HMAC-SHA1[-96]",
+          "primitive": "ae"
+        },
         {
           "standard": [
             {