Update Speakers

[Salomon-Mazatlan]

Final pending adjustments worked on with Van:

• Saved regex, button next to the custom pattern field (visible only with Custom checked); loads, edits (double click, with validation) and deletes the patterns stored in speaker_regex.json; "Use" copies the selected pattern to the field and re-scans; changes persist on close.
• ':'-chained codes: name1: name2: text creates one table row per code, all coding the same segment.
• Chain safeguards: strict Name: pattern (up to 3 word tokens glued to the colon), guards against bare times (10:30), URLs, over-long tokens, duplicated names, blanked time stamps in the gap; max 8 per chain.
• select_items.py: checkbox-selection sync.

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• Minor: _save_regex_store() extracted so the completer and the manager share one writer.

[Salomon-Mazatlan]

This is the last pending update on my side. I have found some minor details along the other py files, but they do not affect how the software behaves; I will keep testing them and we can handle them after the 4-beta release.