download_logic.rs: conditionally call set_file_permissions only for written files

[BillyOutlast]

Problem

In desktop/src-tauri/games/src/downloads/download_logic.rs:141-183, set_file_permissions is called unconditionally in the file-processing loop. When should_write is false and no file is opened/written, permission updates should be skipped.

Proposed Fix

Guard set_file_permissions behind a check that should_write is true and the file was actually opened/written. Preserve permission updates for written files while skipping them for files handled only by stream consumption.

Priority

Low — minor inefficiency; no functional impact.