Stop the session list saying "Couldn't reach the server" twice

On screen it read: "Couldn't reach the server: Couldn't reach the server at
https://10.0.2.2:8443 (ConnectException ...)". Api.kt writes a whole
sentence -- the address, the exception, and what to check -- because that
message has to be actionable on a device with no logcat; the list then
prefixed it with a shortened version of the same claim. The usage screen,
showing the identical failures, prints the message alone and reads
correctly, so this was one caller disagreeing with the other about what a
failure looks like.

The prefix was also a guess the caller could not make. `LoadState.Error`
here also carries a failed *delete*, which the server may well have
answered -- reaching it fine and refusing -- and the prefix said it had
not been reached at all.

Found by looking at it with the server stopped, which is the only way this
was ever going to show up: it compiles, and the happy path looks perfect.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017xn8nHw1tw1R6PtiY1eEtw

app/androidApp/src/main/kotlin/com/example/aiapp/SessionListScreen.kt

@@ -86,8 +86,14 @@ fun SessionListScreen(
 
             when (val state = listState) {
                 is LoadState.Loading -> CircularProgressIndicator()
+                // The message as Api.kt wrote it, with nothing added: it is
+                // already a whole sentence naming the address and what to
+                // check, so a prefix here read "Couldn't reach the server:
+                // Couldn't reach the server at ...". It was also a guess --
+                // a delete that the server itself refused had reached it
+                // fine.
                 is LoadState.Error -> Text(
-                    "Couldn't reach the server: ${state.message}",
+                    state.message,
                     color = MaterialTheme.colorScheme.error,
                 )
                 is LoadState.Loaded -> {