Guard composite ML-DSA keyId check with WOLFSSH_NO_MLDSA

wolfSSH_ProcessBuffer() referenced the composite key IDs
(ID_MLDSA44_ES256 etc.) unconditionally when rejecting non-composite
OpenSSH-format private keys, but those IDs are only declared inside
#ifndef WOLFSSH_NO_MLDSA in wolfssh/internal.h. Any build linked
against a wolfSSL without HAVE_DILITHIUM (ie without --enable-mldsa)
fails to compile as a result -- this was the cause of every CI job
failing on this branch, not just the ML-DSA-specific ones.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: Emma Stensland

src/internal.c

@@ -3257,10 +3257,13 @@ int wolfSSH_ProcessBuffer(WOLFSSH_CTX* ctx,
          * openssh-key-v1 envelope later (SendKexGetSigningKey()); every
          * other key type expects raw DER, so reject them here instead of
          * silently storing an envelope that will fail every handshake. */
-        if (format == WOLFSSH_FORMAT_OPENSSH &&
-                keyId != ID_MLDSA44_ES256 && keyId != ID_MLDSA65_ES256 &&
+        if (format == WOLFSSH_FORMAT_OPENSSH
+#ifndef WOLFSSH_NO_MLDSA
+                && keyId != ID_MLDSA44_ES256 && keyId != ID_MLDSA65_ES256 &&
                 keyId != ID_MLDSA87_ES384 && keyId != ID_MLDSA44_ED25519 &&
-                keyId != ID_MLDSA65_ED25519 && keyId != ID_MLDSA87_ED448) {
+                keyId != ID_MLDSA65_ED25519 && keyId != ID_MLDSA87_ED448
+#endif
+                ) {
             WS_FORCEZERO(der, derSz);
             WFREE(der, heap, dynamicType);
             return WS_UNIMPLEMENTED_E;