perf(compiler): optimize multi-return tuple assignment with move semantics
- Replace temporary Var construction with direct tuple element assignment
- Implement std::move for final local variable uses to avoid unnecessary copies
- Track remaining variable uses to determine when to apply move semantics
- Preserve PHP value-assignment semantics for references and indirect zvals
- Add comprehensive test coverage for tuple multi-return scenarios
- Include tests for repeated values, references, globals, and static variables
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韩天峰