feat(pinocchio): optimize performance to 283 CU and enhance memory safety

[raushan728]

Optimized p-memo base execution and enhanced memory safety.

Performance (Sub-300 CU)

• Base Case (0 signers): 283 CU (9.6% reduction from 313).
• Empty Memo: 139 CU.
• Max Memo (1232b): 1985 CU.

Engineering

• Optimization: Replaced pinocchio_log macros with direct sol_log_ syscalls.
• Safety: Replaced instruction_data_unchecked() with safe instruction_data()? access.
• Consistency: Explicitly validated UTF-8 to return InvalidInstructionData, aligning with SPL standard.
• Tests: Added functional coverage for 0-byte and maximum MTU-sized memos.