Fix false positive stream ready timeout warning (#515)

The timeout task was logging a warning even when cancelled (streams signaled ready in time). The `try?` swallowed the `CancellationError` but then continued to log the warning.

Now uses `do/catch` to only log when the sleep actually completes (true timeout), not when cancelled.

**Before:** Every app launch logged 5+ "Stream ready timeout - proceeding anyway" warnings even though streams were working fine.

**After:** Warning only appears if streams genuinely fail to signal ready within 10 seconds.

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> [!NOTE]
> ### Suppress false stream-ready warnings by gating the 10‑second timeout task in `ConvosCore.Syncing.SyncingManager`
> Wrap the stream readiness timeout task in `do/try/catch` so `Task.sleep(10s)` cancellation is swallowed and `Log.warning` plus finishing of `messageStreamReadyContinuation` and `conversationStreamReadyContinuation` only occur after an actual timeout in [SyncingManager.swift](https://github.com/xmtplabs/convos-ios/pull/515/files#diff-ba2362cf646b78283a1af17654ea8d2c18f6b1cb686a78e7761e10f1b0328101).
>
> #### 📍Where to Start
> Start at the timeout task closure inside `SyncingManager`’s stream readiness logic in [SyncingManager.swift](https://github.com/xmtplabs/convos-ios/pull/515/files#diff-ba2362cf646b78283a1af17654ea8d2c18f6b1cb686a78e7761e10f1b0328101).
>
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Author: yewreeka

ConvosCore/Sources/ConvosCore/Syncing/SyncingManager.swift

@@ -443,11 +443,15 @@ actor SyncingManager: SyncingManagerProtocol {
             // AsyncStream doesn't respond to task cancellation, so we must finish the
             // continuations to unblock the waiting tasks when timeout fires.
             group.addTask {
-                try? await Task.sleep(for: .seconds(10))
-                Log.warning("Stream ready timeout - proceeding anyway")
-                // Finish continuations so waiting tasks complete (AsyncStream ignores cancelAll)
-                messageStreamReadyContinuation?.finish()
-                conversationStreamReadyContinuation?.finish()
+                do {
+                    try await Task.sleep(for: .seconds(10))
+                    Log.warning("Stream ready timeout - proceeding anyway")
+                    // Finish continuations so waiting tasks complete (AsyncStream ignores cancelAll)
+                    messageStreamReadyContinuation?.finish()
+                    conversationStreamReadyContinuation?.finish()
+                } catch {
+                    // Task was cancelled because streams signaled ready in time - no warning needed
+                }
             }
 
             // Wait for both streams to be ready OR timeout