* fix(browser): publish captured screenshots and fetches atomically
_write_screenshot and _write_capture_output wrote the final path with a truncating
write and then returned its name, so a failure part-way through left a partial
capture that the caller reported as saved - and the leftovers then made the dedupe
helper pick a new name for the next capture. Publish through a temporary file plus
os.replace.
* fix(browser): preserve permissions on atomic capture publication
---------
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
