Fix bytecode my-extraction, stat on filehandles, and signatures.t regression

[fglock]

Summary

• Bytecode my-extraction in short-circuit ops: Extract my declarations before conditional jumps in &&/||/// so variables are always initialized to undef even when the branch is short-circuited (e.g., my $x = expr if COND)
• AUTOLOAD with forward declarations: Fix AUTOLOAD dispatch when a forward-declared stub exists — use InheritanceResolver to find the real AUTOLOAD in the inheritance chain
• Stat/file tests on filehandles: Store filePath in RuntimeIO at open() time so stat($fh) and -f $fh work correctly instead of returning EBADF
• stat _ parsing: Move the special _ handler before the ALLCAPS bareword check in OperatorParser.parseStat() so stat _ uses the last-stat buffer
• stat _ / lstat _ cached buffer: Use cached stat attributes instead of re-statting; return EBADF when no prior stat succeeded
• Signatures.t regression fix: Move package inheritance from BytecodeCompiler.compile() to EmitterMethodCreator.compileToInterpreter() — the generic compile() path was clobbering the correct eval STRING package set by setCompilePackage(), breaking 155 signature tests
• Signature error messages: Use "expected N" instead of "expected at most/least N" when min == max parameters

Test plan

• ./gradlew test passes
• t/op/signatures.t: 307 failures (down from 462 regression, matching baseline)
• t/op/stat_errors.t: 0 failures
• ExifTool.t: 30/35 pass

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