fix(rust): remove unused assignments in tv_screen.rs

[cfsmp3]

Summary

Remove three unused assignments to time_show.time_in_ms in src/rust/src/decoder/tv_screen.rs that were flagged by Clippy as "value assigned is never read".

Issue

Clippy reported warnings:

warning: value assigned to `time_show` is never read
   --> src/decoder/tv_screen.rs:457:17
warning: value assigned to `time_show` is never read
   --> src/decoder/tv_screen.rs:469:17
warning: value assigned to `time_show` is never read
   --> src/decoder/tv_screen.rs:476:17

Root Cause

The code pattern was:

1. Subtract frame delay from time_show.time_in_ms
2. Use the modified value in get_scc_time_str(time_show)
3. Add frame delay back (restore original value)

However, since time_show is not used after the match statement ends, the restoration assignments (step 3) were unnecessary dead code.

Changes

Removed the three unnecessary += 1000 / 29.97 as i64 assignments at the end of each match branch.

Test plan

• Code compiles without errors
• Clippy warnings for tv_screen.rs are resolved
• Existing tests pass

🤖 Generated with Claude Code