* android, desktop, ios: remove left padding on consecutive received messages in channels
In channels, a received message that does not show an avatar (a consecutive post from the same sender) drops the avatar-sized left padding and sits flush-left. Applies to both owner broadcasts (ChannelRcv) and contributor posts (GroupRcv); the first message of each run still shows the avatar. Gated on ChatInfo.isChannel, so regular groups, business and direct chats, sent messages, and avatar-shown messages are unchanged.
* docs: add plan justifying removing left padding on consecutive received messages in channels
* ios: fix right gap on consecutive received messages in channels
Removing the avatar-sized left padding from no-avatar received messages
(this PR) shifted those bubbles ~44pt left, but maxWidth still reserved
the avatar inset, so consecutive messages stopped ~44pt short of the
first (avatar) message on the right.
Widen maxWidth for no-avatar channel-received items so their right edge
matches the avatar-shown first message. The no-avatar predicate reuses
the exact shouldShowAvatar expression from the render path (lifted to a
file-scope function so the maxWidth site can call it), so the width and
the rendered layout can never disagree.
Android is unaffected: Compose derives content width from padding, so
reducing the start padding already widened the row there.
* ios: increase left padding
* kotlin: increase left gap
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Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>
Co-authored-by: Evgeny Poberezkin <2769109+epoberezkin@users.noreply.github.com>