preprocess report does not included the preprocessed information on duration

### Bug description

When running the preprocess step, 2 reports are generated in the outpot file.

Below example we see the partial report on top and at the end the final.

```
more PREP_thr_long.o5312102
Partial report showing only audio statistics:
type quantity
-------------------------- ----------
processed files 0
previously processed files 300
missing files 0
audio_empty 0
audio_too_short 0
audio_too_long 0
duration 0h 32m 43s
╭───────────────────────────── Congratulations 🎉 ─────────────────────────────╮
│ You've finished preprocessing: audio, spec, attn, text, pitch, energy. Your │
│ files are located at │
│ /gpfs/fs5/nrc/nrc-fs1/ict/others/u/tes001/TxT2SPEECH/LJ_TEST_compare/300_thr │
│ _long/preprocessed. Here is a report: │
│ type quantity │
│ -------------------------- ---------- │
│ processed files 0 │
│ previously processed files 300 │
│ missing files 0 │
│ missing symbols 0 │
│ skipped processes 0 │
│ nans 0 │
│ audio_empty 0 │
│ audio_too_short 0 │
│ audio_too_long 0 │
│ duration 0h 32m 43s │
╰─ Next Steps Documentation: https://docs.everyvoice.ca/stable/guides/custom/ ─╯
```

Where the final preprocess audio "30:39.42" is not being reflected in the final part of the report :
```
(EveryVoice_2025-08-01) [U24-GPSC5]:$ soxi preprocessed/audio/*.wav
Total Duration of 301 files: 00:30:39.42
```

The initial report duration is correct on the raw files:
`Total Duration of 300 files: 00:32:43.24`

### How to reproduce the bug

Run `everyvoice preprocess` with audio trimming during the wizard

### Error messages and logs

No error messages

### Environment

Latest enviroment

### More info

_No response_

Reproduce the issue with `everyvoice preprocess` and audio trimming enabled, comparing the partial and final reports with the `soxi preprocessed/audio/*.wav` duration. Trace where the preprocessing report is assembled and ensure the final duration reflects the generated preprocessed audio files.

Written by the indexing model from the issue text.