Fix attachment de-dup stripping real digits from the filename

[Osamaali313]

What

email_download_attachment corrupts the filename when it de-duplicates a name collision. The rename loop:

while target.exists():
    target = (
        scratch.path
        / f"{target.stem.rstrip('-0123456789') or 'attachment'}-{counter}{target.suffix}"
    )
    counter += 1

str.rstrip('-0123456789') removes every trailing digit/dash, including digits that are part of the real name. It was only meant to strip a previously-appended -N suffix before adding the next one.

Why it matters

Downloading two attachments with the same digit-ending name into one session folder mangles the filename:

attachment	current	expected
invoice_2024.pdf	invoice_-1.pdf	invoice_2024-1.pdf
IMG_20240115.jpg	IMG_-1.jpg	IMG_20240115-1.jpg
image001.png (Outlook auto-name)	image-1.png	image001-1.png
report.pdf (no digits)	report-1.pdf	report-1.pdf

The wrong name is written to disk and returned as path in the tool result.

How

Strip only a trailing -<number> suffix:

/ f"{re.sub(r'-[0-9]+$', '', target.stem) or 'attachment'}-{counter}{target.suffix}"

re is already imported. Verified this preserves the original digits and still increments correctly on repeated collisions (invoice_2024.pdf → invoice_2024-1.pdf → invoice_2024-2.pdf). Names without a trailing -N are unchanged.

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