fix(es/22_Call): handle failed low-level getX calls

[buyua9]

Summary

• Handle failed low-level getX() calls before decoding return data.
• Emit Response(false, data) and return an explicit fallback value on failure; decode only successful return data.

Why

The Spanish tutorial's callGetX() ignored the success flag and unconditionally decoded data. A failed low-level call can return an invalid or empty buffer, causing a generic decode revert instead of demonstrating an explicit failure path.

Validation

• git diff --check and failure-branch assertions passed.
• npx solc@0.8.34 --base-path . --bin Languages/es/22_Metodo_llamar_es/Call.sol passed with the existing payable-fallback warning.
• codespell reported no findings.
• Strict pr-value gate: R=88, L=100, p_submit_worthy=0.9977.