The Send button gets a name

Every other icon-only control in the composer row takes its label from
`IconAction(label =)`. Send is a bare Button whose Icon passed
`contentDescription = null`, so the single most important control in the
app had no name: TalkBack announced "button", and it was absent from an
accessibility dump altogether, which is also how it came to be reported
as a missing Send button while it sat there working.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/src/main/kotlin/io/flamenet/messenger/app/ChatScreens.kt

@@ -2317,7 +2317,14 @@ fun ColumnScope.ChatScreen(
             ) {
                 Icon(
                     KitIcon.Send,
-                    contentDescription = null,
+                    // Named, unlike every other icon-only control in this row,
+                    // which get theirs from `IconAction(label =)`. This one is
+                    // a bare Button, so a null description left the single
+                    // most important control in the app with no name at all:
+                    // TalkBack announced "button", and it was absent from an
+                    // accessibility dump entirely, which is also how it came
+                    // to be reported as a missing Send button.
+                    contentDescription = "Send",
                     modifier = Modifier.size(Kit.icon),
                 )
             }