Stdlib: openssl_pkey_derive Reflection + named args (#27685)

[PurHur]

Summary

• Restore Zend/php-src Reflection for openssl_pkey_derive() (public_key, private_key, int $key_length = 0 → string|false) — function was absent from php-types InternalArgInfo, so arity was 0 and named args failed with Unknown named parameter.
• PHP-in-PHP only: BuiltinParamNames / BuiltinInternalArgInfo / BuiltinInternalDefaultValues; no runtime/ C.
• php-src ref: ext/openssl/openssl.stub.php.

Closes #27685

Test plan

• Zend vs VM identical on issue repro (Reflection + named soft-fail + unknown peer_key)
• ./script/phpunit.sh test/compliance/OpensslPkeyDeriveReflectionVMTest.php — OK
• ./script/phpunit.sh --filter testOpensslPkeyDeriveNamedParamsResolve test/unit/BuiltinParamNamesAliasTest.php — OK
• ./script/phpunit.sh --filter 'testOpensslPkey|openssl_pkey_derive' test/unit/OpensslModuleTest.php — OK (2 tests)
• php bin/vm.php test/repro/maintainer_gap_openssl_pkey_derive_reflection.php
• Not covered: full ci-local / AOT (runtime already VM-only for derive; Reflection-only change)
• Gate snapshot: inventory OK 7020/7020; north-star5-fast red on master (gen-0 manifest mismatch Self-host M5: bootstrap-inventory argv driver size floor — grow beyond 451KB stub #8713) — unrelated

Verification transcript

=== ZEND === / === VM === (identical)
required=2 argc=3
ret=string|false
public_key REQ
private_key REQ
key_length:int OPT=0
named=false
Unknown named parameter $peer_key

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