Fix attachment de-dup stripping real digits from the filename

The collision-rename loop in email_download_attachment used
`target.stem.rstrip('-0123456789')`, which strips every trailing digit and
dash, not just a previously-appended `-N` suffix. So saving a second
`invoice_2024.pdf` produced `invoice_-1.pdf`, `IMG_20240115.jpg` became
`IMG_-1.jpg`, and Outlook's `image001.png` became `image-1.png`.

Strip only a trailing `-<number>` suffix with a regex, preserving the
original digits (and still incrementing correctly on repeated collisions).

coworker/connectors/email_tools.py

@@ -555,7 +555,7 @@ def make_email_tools(
                     while target.exists():
                         target = (
                             scratch.path
-                            / f"{target.stem.rstrip('-0123456789') or 'attachment'}-{counter}{target.suffix}"
+                            / f"{re.sub(r'-[0-9]+$', '', target.stem) or 'attachment'}-{counter}{target.suffix}"
                         )
                         counter += 1
                     target.write_bytes(payload)