feat: add marginfi-deposit feature

[ChiefWoods]

Summary

Changes

• prerequisite: feat: add extra data to Deposit trait #32
• add marginfi-deposit feature
• scaffold test (just like Jupiter and Kamino)

Testing

• make format
• make clippy
• make test
• make test-upstream (if relevant)

Protocol integration checklist (if applicable)

• Feature flag added and used for all protocol code
• Action context enums updated
• Detection logic updated
• Account parsing validates count and types
• Tests added or updated

[L0STE]

Byte 17 of the CPI instruction data is never written — that's UB.

DEPOSIT_DATA_LEN = 18 is correct (MarginFi expects Borsh Option<bool> = tag + value = 2 bytes), but you're only writing the value:

core::ptr::write(ptr.add(16), data.deposit_up_to_amount.unwrap_or(0)); // writes 1 byte, not 2

You need both the tag and the value:

match data.deposit_up_to_amount {
    None    => { *ptr.add(16) = 0; *ptr.add(17) = 0; }
    Some(v) => { *ptr.add(16) = 1; *ptr.add(17) = v; }
}

Rebase onto #33 once it lands.