fix: update command protocol to separate gestures and factors

[GoodKimchi]

Summary

Updates the frontend and backend to match the current Yeah Hand command protocol.

Changes

• Updated frontend buttons to send gesture commands independently (PINCH, POWER, MONKEY, RELAX).
• Updated backend validation to accept standalone gesture commands and numeric factor values (0–100).
• Updated command handling to match the current protocol, where gesture commands and factor values are sent separately.

Testing

• Verified gesture commands are accepted.
• Verified standalone numeric values (0–100) are accepted.
• Verified combined commands (e.g. PINCH 50) are rejected.
• Verified out-of-range values (e.g. 101) are rejected.