fix: arm64 architecture support - foojay API expects aarch64

[Talbot3]

Bug Report

Summary

The Java plugin fails on macOS ARM64 because the foojay API expects aarch64 but the plugin sends arm64.

Steps to Reproduce

1. Run on macOS ARM64 (Apple Silicon)
2. Execute: vfox install java@17.0.7-zulu
3. Error: attempt to index a non-table object(nil) with key 'links'

Root Cause

1. Architecture mismatch: RUNTIME.archType returns arm64 but foojay API expects aarch64
2. Poor error handling: When API returns empty results, the code crashes with unclear error

API Verification

# Returns empty (wrong)
curl "https://api.foojay.io/disco/v3.0/packages/jdks?version=17.0.7&distribution=zulu&architecture=arm64..."

# Returns 2 results (correct)
curl "https://api.foojay.io/disco/v3.0/packages/jdks?version=17.0.7&distribution=zulu&architecture=aarch64..."

Proposed Fix

lib/foojay.lua - Add architecture conversion:
-- Convert arm64 to aarch64 for foojay API compatibility
local arch = RUNTIME.archType
if arch == "arm64" then
    arch = "aarch64"
end
local reqUrl = URL:format(version, distribution, arch, archive_type, os, lib_c_type)

hooks/pre_install.lua - Better error handling:
if not jdks or #jdks == 0 then
    error("No JDK found for " .. ctx.version .. " on " .. RUNTIME.osType .. "/" .. RUNTIME.archType)
end

Additional Fix

Also removed latest=available parameter from API URL to ensure exact version matching.

Reference

- foojay API: https://github.com/foojayio/discoapi

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