Fix static closure bindTo fatal + restore Error parity (#4613)

[PurHur]

Summary

• Fix VM::returnTypeCallableName() to read func->class->value instead of concatenating the PHPCfg\Operand\Literal object — unblocks methods with class return types such as make(): Closure.
• Reopened Language: static closure bindTo()/bind() with $this must Error (Zend/zend_closures.c parity) #4613: static Closure::bindTo() / Closure::bind() with $this now reach the existing ClosureSupport guard and throw Error: Cannot bind static closure to object on VM and JIT (was fatal before bind path ran).
• Adjust compliance/repro catch blocks to catch (Error) without $e to avoid unrelated catch-slot warning noise in output comparison.

php-src reference

• Zend/zend_closures.c — zend_closure_bind() static-closure guard

PHP implementation

• lib/VM.php — returnTypeCallableName()
• lib/VM/ClosureSupport.php — existing static closure Error (unchanged)

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php test/compliance/cases/language/static_closure_bind.phpt
php bin/jit.php test/compliance/cases/language/static_closure_bind.phpt
php bin/vm.php test/repro/maintainer_gap_static_closure_bind_regression.php
./vendor/bin/phpunit --filter static_closure_bind
'

Output:

Error: Cannot bind static closure to object
Error: Cannot bind static closure to object
object
OK (2 tests, 2 assertions)

Closes #4613

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