Compile java-http-client with public crypto release

[RomeoApps]

This updates the helper java-http-client module to compile against the public scala-native-crypto 0.3.0 release and the current curl/OpenSSL APIs.

Why:

• Support for java.net.http.HttpClient scala-native/scala-native#4104 points Requests-Scala Scala Native support toward java.net.http support.
• Scala-Native Support (1000USD Bounty) com-lihaoyi/requests-scala#156 is still blocked on a usable Scala Native HttpClient path.
• The previous helper snapshot referenced an unpublished dirty scala-native-crypto build and older curl APIs, so a fresh clone could not compile cleanly.

What changed:

• Move scala-native-crypto to public 0.3.0.
• Update curl option/info constants and callback signatures to the current generated APIs.
• Keep KeyStore-backed client certificate initialization explicit as unsupported instead of relying on removed dirty-snapshot internals.
• Adjust the related compile test to assert that unsupported boundary.

Validation:

• git diff --check
• ./mill -i modules.java-http-client.compile
• ./mill -i modules.java-http-client.test.compile
• Public patch apply was also checked against a fresh clone.

Known limit:

• Full native test execution is still blocked on my local machine by missing OpenSSL headers (openssl/ssl.h), so this PR is scoped to restoring clean compile/test-compile and making the unsupported client-certificate path explicit.

[RomeoApps]

Validation update: I reran the native compile/link locally with OpenSSL 3.5.0 provided via CPATH, LIBRARY_PATH, DYLD_LIBRARY_PATH, and PKG_CONFIG_PATH. The previous openssl/ssl.h blocker is gone: modules.java-http-client.test.compile and modules.java-http-client.test.nativeLink complete successfully, and the native linker now links [pthread, dl, m, crypto, curl, ssl].

I also ran a focused non-network smoke slice:

modules.java-http-client.test.testOnly snhttp.test.java.net.CookieHandlerTest snhttp.test.java.net.CookieManagerTests snhttp.test.java.net.http.HttpClientBuilderTest

Result: Tests: 45, Passed: 45, Failed: 0.

I’m not claiming the full modules.java-http-client.test suite is green yet: after link it reaches HttpClientTest and appears to hang in the existing HTTP request loop, so I stopped that run rather than over-reporting it. The compile/link issue this PR targets is now validated locally.

[RomeoApps]

Follow-up pushed in 8aa963b.

What changed:

• fixed the curl multi wait loop so it stops once the multi handle reports no running transfers, instead of polling forever after completion;
• decoded the CURLMSG_DONE payload from the pointer-sized union slot before mapping libcurl result codes, so invalid-host and unreachable-port paths now become ConnectException;
• made client KeyManager registration fail explicitly as unsupported, and adjusted the unsupported-boundary test so it no longer depends on unavailable KeyStore.getInstance.

Validation with the same local OpenSSL 3.5.0 include/lib/pkg-config paths:

• git diff --check
• modules.java-http-client.test.testOnly snhttp.test.java.net.http.HttpClientTest -> Tests: 5, Passed: 5, Failed: 0
• previous non-network smoke slice -> Tests: 45, Passed: 45, Failed: 0
• modules.java-http-client.test -> Tests: 463, Passed: 463, Failed: 0

This is still not a full Requests-Scala bounty claim from this PR alone; it makes the helper PR green locally and removes the previous HttpClientTest hang/full-suite blocker.