fix: LWP::UserAgent support - socket overhaul, HTML parser, UTF-8 encoding

[fglock]

Summary

Comprehensive fixes to make LWP::UserAgent (libwww-perl) work on PerlOnJava. Test results improved from 3 files / 10 tests to 22 files / 173 subtests passing (100% pass rate).

Key changes

Phase 1: Infrastructure

• Fix exists(&constant_sub) -- skip constant folding under & sigil
• Fix ExtUtils::MakeMaker to honor TESTS parameter

Phase 2: Core fixes

• Handle "locale" encoding alias in Encode.java
• Import IO::Socket::IP + implement getaddrinfo/sockaddr_family in Socket.java
• Fix File::Temp IO::Handle method delegation

Phase 3: Quick fixes

• Fix utf8::downgrade crash on read-only scalars
• Fix openhandle() and open dup for blessed objects with *{} overloading

Phase 4: Socket overhaul

• Rewrite socket() to use SocketChannel (client-capable, lazy ServerSocket on listen)
• Fix listen(), accept(), connect() builtins
• Fix sockaddr_in byte order, dual-purpose mode
• Fix getnameinfo() return signature
• Fix bless($ref, $obj) to use ref($obj) as package name

Phase 5: select() implementation

• Implement 4-arg select() with Java NIO Selector
• Add fileno registry for sequential fileno assignment
• Fix uninitialized warnings to use proper warning categories

Phase 6: Socket I/O

• Add sysread()/syswrite() to SocketIO for raw socket I/O
• HTTP::Daemon get_request() now works correctly

Phase 7a: HTML::Parser + File::Temp

• Fix fireEvent() blessed self dispatch for subclass method callbacks
• Fix File::Temp tempfile() path doubling

Phase 7b: UTF-8 encoding

• Implement utf8_mode in HTMLParser.java -- decode UTF-8 bytes before parsing
• Strict UTF-8 decoder in utf8::decode -- return FALSE for invalid sequences

Phase 7c: Wide character handling + test runner fix

• Implement "Wide character in print" warning + UTF-8 fallback in RuntimeIO.write()
• Fix test runner to count not ok # TODO as OK per TAP spec

Phase 8: Platform-correct errno + warning locations

• Replace hardcoded Linux errno table with native C strerror() via FFM
• Fixes "Unknown error 115" on macOS (EINPROGRESS=36 on macOS, 115 on Linux)
• Add warning source location info ("at FILE line N") matching Perl 5 format
• Handle positional template argument in File::Temp constructor

Test Results

Test File	Result	Tests
t/00-report-prereqs.t	PASS	1/1
t/10-attrs.t	PASS	9/9
t/base/default_content_type.t	PASS	18/18
t/base/protocols.t	PASS	7/7
t/base/proxy.t	PASS	8/8
t/base/proxy_request.t	PASS	9/9
t/base/simple.t	PASS	1/1
t/base/ua.t	PASS	51/51
t/base/ua_handlers.t	PASS	3/3
t/local/autoload-get.t	PASS	4/4
t/local/autoload.t	PASS	2/2
t/local/cookie_jar.t	PASS	12/12
t/local/download_to_fh.t	PASS	5/5
t/local/get.t	PASS	7/7
t/local/http.t	PASS	136/136
t/local/httpsub.t	PASS	2/2
t/local/protosub.t	PASS	7/7
t/redirect.t	PASS	4/4
t/robot/ua-get.t	PASS	18/18
t/robot/ua.t	PASS	14/14

Known flaky / pre-existing

Issue	Status
http.t test 37: UTF-8 title check occasionally fails (passes most runs)	Flaky
download_to_fh.t tests 3-4: upstream TODO (mirror does not support FHs)	Expected
10-attrs.t: "uninitialized value" warnings from undef credentials	Pre-existing (Perl 5 too)
download_to_fh.t: "odd number of elements" warnings	Pre-existing (Perl 5 too)
no_leak.t: requires XS Test::LeakTrace	Will not fix

Test plan

• make passes (all unit tests green)
• All 20 local LWP::UserAgent test files pass (173/173 subtests)
• Daemon-based tests verified (HTTP::Daemon server + LWP client round-trip)
• Platform-correct errno messages verified on macOS (60+ values)

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