fix: enable jcpan -t Text::vCard and Directory::Scratch

[fglock]

Summary

Investigation of jcpan -t Text::vCard (originally 16/18 test programs failing, 9/11 subtests failed) and the related Directory::Scratch test failures uncovered eight independent PerlOnJava bugs. This PR fixes all of them, taking both modules to a clean test pass and fixing several general-purpose IO/parser issues along the way.

Bundled-module fixes (Text::vCard prereqs)

• MIME::QuotedPrint declares $VERSION and re-exports encode/decode aliases. Without $VERSION, use MIME::QuotedPrint 3.07 died with "does not define $MIME::QuotedPrint::VERSION".
• File::Spec now sets @ISA = ("File::Spec::$platform") based on $^O instead of just (Exporter). Modules like Directory::Scratch and Path::Class derive the platform from $File::Spec::ISA[0]; without this they passed an empty string to _spec_class() and died with "Invalid system type ''".
• New Unicode::LineBreak shim providing the minimal Unicode::GCString API (new/length/substr/as_string/columns) that Text::vCard::Node uses. Pure Perl, splits with \X for graphemes.

Interpreter & operator fixes

• bless now emits the upstream "Use of uninitialized value $class in bless" and "Explicit blessing to '' (assuming package main)" warnings when given an undef class, matching real Perl. Tests like like $@, qr/Use of uninitialized value/ previously got an empty $@.
• chmod $mode, @paths no longer silently no-ops. Operator.chmod was iterating runtimeList.elements directly, so an unflattened RuntimeArray slot stringified as ARRAY(0x...). Now flattens via addToList(...) like UnlinkOperator.
• chomp / chop are now parsed as named-unary operators when used without parentheses. So is(chomp @a, 3, "ok") parses as is(chomp(@a), 3, "ok") — matching real Perl deparse output — instead of letting chomp gobble all of is()'s arguments.
• Slurp-mode <$fh> on an empty file now returns the empty string on the first call and undef only on the second call. Previously it returned undef immediately, which broke Path::Tiny->slurp on empty files (and Directory::Scratch on top of that).
• flock no longer leaks JVM-wide shared locks across abandoned Perl handles. Path::Tiny's slurp-then-append-with-truncate idiom used to fail with "Resource deadlock avoided" because the SHARED registry entry from the slurp's lexical $fh outlived the Perl scope. Added a Cleaner-based safety net plus a reactive reclaimAbandonedSharedLock retry path on EX-lock acquisition.

Test plan

• make — full PerlOnJava unit-test suite passes.
• ./jcpan -t Text::vCard — 18/18 test programs, 155/155 subtests pass.
• ./jcpan -t Directory::Scratch (run via Test::Harness from blib) — 35/35 test programs, 691/691 subtests pass.

Files changed

src/main/java/org/perlonjava/runtime/operators/Operator.java
src/main/java/org/perlonjava/runtime/operators/Readline.java
src/main/java/org/perlonjava/runtime/operators/ReferenceOperators.java
src/main/java/org/perlonjava/runtime/io/CustomFileChannel.java
src/main/java/org/perlonjava/frontend/parser/CoreOperatorResolver.java
src/main/java/org/perlonjava/frontend/parser/OperatorParser.java
src/main/perl/lib/MIME/QuotedPrint.pm
src/main/perl/lib/File/Spec.pm
src/main/perl/lib/Unicode/LineBreak.pm   (new)
src/main/java/org/perlonjava/core/Configuration.java   (auto, gitCommitId)

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