fix(sound): consume Director dispatch argument

[benletchford]

Closes #583.

Director 3 uses the private SoundDispatch selector $00640004 as a Pascal procedure with one INTEGER argument. Its literal selector has a zero encoded parameter count, so the generic unknown-selector path left that word on the stack and the extension eventually returned through it as an address.

Teach the selector-size table its historical two-byte frame and handle the procedure without writing a nonexistent result slot. The caller return address immediately above the argument remains intact. A focused regression pins both the stack adjustment and preserved return address.

Verification:

• cargo test --lib --quiet (2,950 passed, 3 ignored)
• cargo check --no-default-features --quiet
• cargo clippy --lib --quiet
• cargo fmt --all -- --check
• The official Journeyman Project Director 3 demo completes 2,000,000 instructions and reaches later UI frames instead of halting at 604,266 instructions on invalid PC $0000003B.