feat: support Loongnix JDKs on Linux loong64

[aooohan]

Foojay rejects loong64, so Java discovery currently returns no usable versions on LoongArch. Add a Loongnix archive provider for Linux loong64: default search and search java all list its GA JDK tarballs, while explicit lnxabi1 and lnxabi2 distribution suffixes select the upstream ABI variant.

For example, vfox install java@21-lnxabi2-fx resolves the newest matching Java 21 JavaFX package for ABI2. Search results use Java version/build numbers and retain ABI and JavaFX suffixes through PreUse. MIPS and EA archives are excluded, version sorting handles GA base releases versus patch updates, and other platforms continue to use Foojay. Both READMEs explain ABI selection and upstream compatibility requirements.

Validation:

• Reproduced the original loong64 request incorrectly reaching Foojay before implementing the provider.
• Offline hook tests pass against 117 archive versions, covering historical/exact/prefix matching, ABI and JavaFX selection, sorting, aliases, platform guards, upstream failures, and existing Foojay routing. Existing PreUse tests also pass.
• The actual vfox 1.0.12 runtime, with linux/loong64 simulated in a temporary plugin copy, reads 117 versions from the live archive. Java 8 ABI2 and Java 21 ABI1/ABI2 download URLs return HTTP 200 and preserve their version through PreUse.
• Inspected partial Java 21 archives for both ABIs: bin/java is beneath a single JDK root, matching the core unpacker layout.
• Native macOS ARM64 OpenJDK/Temurin/Zulu search and download-metadata checks, package validation, and actionlint pass.

No LoongArch hardware was available: actual JDK execution on either ABI remains unverified. This does not publish a plugin release.

Fixes #2