Replace magic number `10_000` with `BASIS_POINTS_TOTAL` constant in `calc.rs`

[Kingsman-99]

Description

distribute_with_remainder in contracts/split/src/calc.rs does not use BASIS_POINTS_TOTAL from types.rs. Any inline use of the literal 10_000 in calc.rs should be replaced with BASIS_POINTS_TOTAL (or BASIS_POINTS_TOTAL as i128) for consistency and to keep the constant as the single source of truth.

Acceptance Criteria

• Import BASIS_POINTS_TOTAL from crate::types in contracts/split/src/calc.rs
• Replace any literal 10_000 in calc.rs with BASIS_POINTS_TOTAL as i128 (or u32 as appropriate)
• Add a note in the distribute_with_remainder doc comment mentioning typical denom values
• cargo test passes

Context

• Target file: contracts/split/src/calc.rs
• BASIS_POINTS_TOTAL is declared in contracts/split/src/types.rs