fix(rust): correctly count and store multiple input files

[cfsmp3]

Summary

• Fix bug where num_input_files was always set to 1 regardless of how many input files were provided
• Fix bug where input files were stored at wrong indices (0, 10, 20... instead of 0, 1, 2...)

Root Cause

Two bugs in the Rust argument parsing code prevented multi-file processing from working:

Bug 1: Incorrect iteration in common.rs:216

// BUG: .iter() on Option<Vec<String>> yields 0 or 1 items (the Vec itself), not Vec contents
options.inputfile.iter().filter(|s| !s.is_empty()).count()

// FIX: Iterate over the Vec contents
options.inputfile.as_ref().unwrap().iter().filter(|s| !s.is_empty()).count()

Bug 2: Wrong indexing in parser.rs:append_file_to_queue()

The function used inputfile.len() as the index for new files, but after resize(10, String::new()), the length becomes 10 even with only 1 file. This caused the second file to go to index 10, third to index 20, etc.

Fixed by simply using push() instead of manual index calculation.

Test plan

• Build ccextractor with fixes
• Test with multiple input files: ccextractor file1.mpg file2.mpg file3.mpg -o output.srt
• Verify all files are opened (check for "Opening file:" messages)
• Verify no crash occurs
• Run cargo clippy - no warnings on changed files

Fixes #1810

🤖 Generated with Claude Code

[ccextractor-bot]

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results, when compared to test for commit 1b0808b...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	7/7
DVD	3/3
DVR-MS	2/2
General	27/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	84/86
Teletext	21/21
WTV	13/13
XDS	28/34

Your PR breaks these cases:

• ccextractor --fixpadding c83f765c66...
• ccextractor --in=ps e9b9008fdf...
• ccextractor --autoprogram --out=srt --latin1 --ucla d037c7509e...
• ccextractor --autoprogram --out=ttxt --latin1 --ucla --xds b22260d065...
• ccextractor --autoprogram --out=srt --latin1 --ucla b22260d065...
• ccextractor --autoprogram --out=srt --latin1 --ucla c813e713a0...
• ccextractor --autoprogram --out=srt --latin1 --ucla 7d2730d38e...
• ccextractor --autoprogram --out=ttxt --latin1 --ucla --xds 0069dffd21...

Congratulations: Merging this PR would fix the following tests:

• ccextractor --hardsubx 1a0302f7fd..., Last passed: Never

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Check the result page for more info.