CPAN Phase 1-4: Modules and Archive::Zip

[fglock]

Summary

This PR implements CPAN Phase 1-4, adding essential modules for CPAN compatibility:

Phase 1: Low-hanging fruit

• DirHandle, Dumpvalue, Sys::Hostname imported via sync.pl
• flock() implemented using java.nio.channels.FileLock
• syscall() implemented with gethostname support

Phase 2: Archive/Network modules

• IO::Socket, IO::Socket::INET, IO::Socket::UNIX
• IO::Zlib, Archive::Tar, Net::FTP
• Socket.pm expanded with 20+ constants
• SysHostname.java XS module
• XSLoader caller() support

Phase 3: Process Control

• IPC::Open2, IPC::Open3 using Java ProcessBuilder
• pipe(), fcntl(), ioctl() operators
• ProcessInputHandle/ProcessOutputHandle for process I/O

Phase 4: CPAN Client Evaluation & Archive::Zip

• Archive::Zip implemented using java.util.zip
  • Read/write zip files
  • Add files, strings, directories
  • Extract individual or all members
• cpanm analysis: Requires ExtUtils::MakeMaker (runs make) - not feasible for PerlOnJava
• User documentation: docs/guides/using-cpan-modules.md

Bug fixes along the way

• Regex octal escape parsing for \10-\377
• Parser fix for @{${...}} nested dereference
• defined *$var regression fix
• Readline on undefined filehandle fix
• Pipe I/O interruptible by alarm signals

Test plan

• Archive::Zip: create, read, extract zip files
• Zip files are valid (verified with system unzip)
• Build passes: ./gradlew build -x test

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