Fix ExifTool compatibility and package refactoring

[fglock]

Summary

This branch contains a collection of fixes aimed at improving ExifTool compatibility and fixing various bugs discovered during testing:

Regex & Capture Groups

• Store capture groups in explicit lastCaptureGroups array instead of relying on globalMatcher.group() which could throw IllegalStateException after certain match sequences. Captures are now explicitly managed: updated on successful capturing matches, cleared on non-capturing or failed capturing matches, preserved across failed non-capturing matches.
• Dynamic scoping for regex match variables via RegexState save/restore of lastCaptureGroups
• Two-tier regex state scoping: subroutine-level (unconditional save/restore at method boundaries) and block-level (conditional, gated by RegexUsageDetector for blocks containing regex ops)
• Fix blockIsSubroutine annotation for named subs so block-level regex save/restore is correctly skipped for subroutine body blocks (set in createRuntimeCode())
• Safe matcher access: use saved lastMatchedString/lastMatchStart/lastMatchEnd fields instead of globalMatcher.group(0)/start(0)/end(0) to avoid IllegalStateException after s///g
• Materialize special vars before regex state restore: $1, $&, etc. in return values are resolved to concrete scalars before the subroutine-level restore overwrites global regex state
• Fix regex octal escapes inside character classes
• Fix \G regex anchor and grep scalar context in bytecode interpreter
• Fix non-/g regex matches incorrectly using pos()

eval & Package Scoping

• Fix eval STRING corrupting outer scope my variables during recursive calls - cleanup aliases from GlobalVariable in finally block
• Fix eval package scoping - restore currentPackage after DynamicVariableManager push
• Fix eval BLOCK and eval STRING in bytecode interpreter
• Scope eval currentPackage via DynamicVariableManager to prevent leaking

File Operations & stat

• Fix stat _ / lstat _ to use cached stat buffer instead of re-statting
• Fix file test operators on filehandles and stat _ caching/parsing
• Fix stat _ parsing edge cases

Bytecode Interpreter

• Add goto LABEL support in bytecode interpreter
• Add labeled block support and fix split args casting
• Fix foreach with pre-declared lexical variable
• Fix HASH_SET and NOT opcodes for non-scalar registers
• Fix undef $scalar, HASH_SET read-only, print return value, MY_SCALAR opcode
• Disable tryWholeBlockRefactoring to fix return inside loops

Other Fixes

• Fix AUTOLOAD dispatch order: search full MRO before AUTOLOAD
• Fix prototype @ argument parsing with parenthesized expressions
• Fix unpack float/double for non-UTF8 binary data
• Fix Encode::is_utf8 returning inverted result
• Fix BYTE_STRING propagation, sort SUBNAME LIST, foreach lexical restore, substr lvalue
• Fix ScalarSpecialVariable not resolving in copy/set operations
• Fix sysread/read type corruption on tied scalars
• Fix scalar localtime/gmtime to use Perl ctime format
• Fix list slice with range indices: (expr)[0..2] now works correctly
• Fix signatures regression and error messages

Test plan

• All 154 unit tests pass
• re/subst.t: 183/281 (matches master) in both JVM and interpreter modes
• ExifTool test suite compatibility (in progress)

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