feat(real-world-vfc-slice): add labeled OpenSSL/Firefox/Chromium/curl pair corpus

Harvest 176 isolated vuln-vs-fix functions (109 CVEs, 352 training rows)
into benchmarks/pairs/vfc with provenance and a JSONL training manifest.
Score the slice as an honesty dashboard (ousast pairs --slice vfc);
keep the pair gate on the local fixtures only.

benchmarks/pairs/vfc/openssl-cve-2023-2975/fixed.c

@@ -0,0 +1,40 @@
+/* Provenance: openssl/openssl siv_cipher (fixed).
+ * repo: openssl/openssl
+ * commit: 00e2f5eea29994d19293ec4e8c8775ba73678598
+ * parent: 175fa8469fc78f6cf35dfb87d26899e60e9ff1d4
+ * commit_url: https://github.com/openssl/openssl/commit/00e2f5eea29994d19293ec4e8c8775ba73678598
+ * cve: CVE-2023-2975
+ * license: Apache-2.0
+ * function: siv_cipher
+ * relpath: providers/implementations/ciphers/cipher_aes_siv.c
+ */
+
+static int siv_cipher(void *vctx, unsigned char *out, size_t *outl,
+                      size_t outsize, const unsigned char *in, size_t inl)
+{
+    PROV_AES_SIV_CTX *ctx = (PROV_AES_SIV_CTX *)vctx;
+
+    if (!ossl_prov_is_running())
+        return 0;
+
+    /* Ignore just empty encryption/decryption call and not AAD. */
+    if (out != NULL) {
+        if (inl == 0) {
+            if (outl != NULL)
+                *outl = 0;
+            return 1;
+        }
+
+        if (outsize < inl) {
+            ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
+            return 0;
+        }
+    }
+
+    if (ctx->hw->cipher(ctx, out, in, inl) <= 0)
+        return 0;
+
+    if (outl != NULL)
+        *outl = inl;
+    return 1;
+}