Picking an attachment reset the composer to Normal, which dropped an
in-progress edit: the attachment went out as a new message and the
leftover edit text then created another one instead of editing the
original.
Route every attach path through a single resetComposerModeAfterAttaching()
helper that clears Reply/Normal but keeps an edit pending, so the typed
text still edits the original on the next send. This also covers the
multi-item gallery picker added in #6519, which reset the mode
unconditionally.
Reply is still cleared (the attachment becomes the reply).
Fixes#7083.
manfrommedan
55f3a1acfb